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WWW.VIDYARTHIPLUS.COM WWW.VIDYARTHIPLUS.COM K.BALAJI . ().., ST7016 Prefabricated Structures JAYAM COLLEGE OF ENGINEERING AND TECHNOLOGY, DHARMAPURI, TAMILNADU K.BALAJI . ()..,

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WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

ST7016 Prefabricated Structures

JAYAM COLLEGE OF ENGINEERING AND

TECHNOLOGY DHARMAPURI TAMILNADU

KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Unit-1

Design principles

Prefabrication is the practice of assembling components of a structure in

a factory or other manufacturing site and transporting complete assemblies or sub-

assemblies to the construction site where the structure is to be located The term is used

to distinguish this process from the more conventional construction practice of

transporting the basic materials to the construction site where all assembly is carried out

Prefabrication is one of the architectural constructions Large units of a building are

produced in factories to be assembled ready-made on the building site This technique

permits the speedy erection of very large structures Units may include doors stairs

windows wall panels floor panels roof trusses and even entire buildings

Prefabricated building

Prefabricated building is a type of building that consists of several factory-built

components or units that are assembled on-site to complete the unit

The term prefabricated is buildings built in components (eg panels) modules (modular

homes) transportable sections (manufactured homes)It may also be used to refer to

mobile homes

Different Between Prefabricated Constructions and Conventional Type

The conventional method of building a house is to transport bricks timber

cement sand and construction aggregate etc to the site and to construct the house on

site from these materials In prefabricated construction only the foundations and floor

slabs are constructed in this way while sections of walls and roof are prefabricated

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(assembled) in a factory (possibly with window and door frames included) transported to

the site lifted into place by a crane and bolted together

Need for Prefabrication

Cost of construction

shorter construction time

easy of expansion

utilization of material

attractive finishes

highly efficient for weather resistance

single source assurance

insurance advantage

Material Properties In of Prefabricated Structures

Quick to assemble

Cost-effective

Portablemovable

Strong

Waterproof Moisture proof

Fire Resistant

Prefabrication Types

1 Conventional prefabrication construction is the most traditional construction

method where all the construction activities are in-situ practices on site

2 Semi-prefabrication divides as two sub-categories system formwork and non-

structural semi-prefabrication involving a part of in-situ construction activities

and a part of prefabrication Normally the non-structural semi-prefabrication is

applied on faccedilade curtain walls lost form systems and dry wall systems

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3 Comprehensive prefabrication involves a structural part and pre-finished

construction Examples of applications of structural comprehensive prefabrication

include staircases slabs columns and beams and

4 Volumetric off-site fabrication encloses usable space but does not constitute the

whole building Volumetric off-site fabrication is mainly used for lsquofacilitiesrsquo and

includes solutions on office washrooms plant rooms building services risers and

lifts

ADVANTAGES OF PREFABRICATION

1 Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

2 Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

3 Quality control can be easier in a factory assembly line setting than a construction

site setting

4 Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

5 Time spent in bad weather or hazardous environments at the construction site is

minimized

6 Less waste may be generated and in a factory setting it may be easier to recycle it

back into the manufacturing process for instance it is less costly to recycle scrap

metal generated in a metal fabrication shop than on the construction site

7 On-site construction and congestion is minimized

DISADVANTAGES OF PREFABRICATION

1 Careful handling of prefabricated components such as concrete panels or steel and

glass panels is required

2 Attention has to be paid to the strength and corrosion-resistance of the joining of

prefabricated sections to avoid failure of the joint

3 Similarly leaks can form at joints in prefabricated components

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4 Transportation costs may be higher for voluminous prefabricated sections than for

the materials of which they are made which can often be packed more compactly

5 Large prefabricated sections require heavy-duty cranes and precision measurement

and handling to place in position

6 Modular coordination

7 Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit or basic module known as 1M that equals to 100

mm The use of MC is an important factor in IBS effective application as it

completes the industry through quality control and increase of productivity

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MODULAR HOMES

Modular homes are houses divided into multiple modules sections which are

manufactured in a remote facility and then delivered to their intended site of use The

modules are assembled into a single residential building using either a crane or trucks

Steel andor wood framing are common options for building a modular homes Modular

components are typically constructed within a large indoor facility on assembly lines

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Modular homes

Indoor Construction of modular homes

Such dwellings are often priced lower than their site-built counterparts and are typically

more cost-effective to builders and consumers These new homes can be constructed in

less time than it takes to build a home on-siteldquo

Importance of modular homes

1 Indoor construction Assembly is independent of weather which increases work

efficiency and avoids damaged building material

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2 Favourable pricing from suppliers Large-scale manufacturers can effectively

bargain with suppliers for discounts on materials

3 Ability to service remote locations Particularly in countries such as Australia

there can be much higher costs to build a site-built house in a remote area or an

area experiencing a construction boom such as mining towns Modular homes can

be built in major towns and sold to regional areas

4 Low waste With the same plans being constantly built the manufacturer has

records of exactly what quantity of materials is needed for a given job While

waste from a site-built dwelling may typically fill several large dumpsters waste

from a modular dwelling generates much less waste

5 Building Strength According to manufacturers modular homes are generally

designed to be initially stronger than traditional homesFor example replacing

nails with screws and adding glue to joints This is supposed to help the modules

maintain their structural integrity as they are transported on trucks to the

construction site

6 Assembly Time The modules that will combine to form the house are assembled

off-site in a factory These modules can take one to three months to be constructed

but often take as little as 10 days to actually construct when they are first started

Then they are transported to the building site where a crane is brought in to

assemble the modules togetherThe placement of the modules together generally

takes several hours or days

Mobile Homes

Mobile homes or static caravans are prefabricated homes built in factories rather than on

site and then taken to the place where they will be occupied They are usually

transported by tractor-trailers over public roads to sites which are often in rural areas or

high-density developments In some countries they are used for temporary

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accommodation on campsites While these houses are usually placed in one location and

left there permanently or they have the ability to be move

Behind the work fitted at installation to hide the base there are strong trailer frames

axles wheels and tow-hitches The two major sizes are single-wides and double-wides

1 Single-wides are eighteen feet or less in width and 90 feet (27 m) or less in length

and can be towed to their site as a single unit

Double-wides are twenty feet or more wide and are 90 feet (27 m) in length or less and

are towed to their site in two separate units which are then joined together

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Mobile homes

Production Transportation and Erection

Considerations in production

The general rule is that the connection device must be as lsquofoolproofrsquo as possible It

should be possible to place it in the mould correctly oriented and within the necessary

tolerances with a minimum of effort

1 Avoid congestion

At the location of connections additional reinforcing steel embedded plates

inserts block-outs etc are frequently required It is not unusual that so many items are

concentrated in a small location that very little room is left for the concrete It must be

kept in mind that reinforcing bars and prestressing strands which appear as lines on the

drawing take up real space in the elements Reinforcing bars require more space than

their nominal diameter and there must be room for the curvature of bent bars If

congestion is suspected it is helpful to draw large-scale details of the region in question

2 Avoid penetration of the forms

Units requiring holes in the forms should be avoided if possible especially in steel

moulds Exceptions to this rule can be made if there is a substantial amount of repetition

in the production Holes in the forms may be necessary not only because the units are

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protruding from the elements but also for the arrangement used to keep the units in place

during casting The units must also be designed so that they do not make the dismantling

of the form impossible without damage to the form Most forms are supposed to be used

more than once Connection units to be placed in the top surface during casting should be

secured against the edges of the mould using purpose made holding devices These

devices are mostly costly make it more difficult to obtain a smooth surface or the

holding device may hamper the placement of concrete or other surface material The

various disadvantages have to be evaluated before selecting the method However if the

same steel plate is placed in the bottom of the form it can be located with great accuracy

as it can be fixed to the bottom directly

3 Reduce post-stripping work

A plant casting operation is most efficient when the product can be taken directly

to the storage area immediately after removal from the form Any operations required

after stripping and before erection such as special cleaning or finishing welding on

projecting hardware etc should be avoided These operations require additional handling

(increased possibility of damage to the elements) extra workspace and added labour

often with skilled trades Sometimes a trade-off is necessary between penetration of the

forms and post-stripping work

4 Use repetitious details

It is very desirable to repeat details as much as possible Similar details should be

identical even ifit results in a slight over-design

5 Use standard items

Hardware items such as inserts studs steel elements etc should be readily

available standard items that are preferably from more than one supplier It also

simplifies fabrication if similar product items are standardised as to size and shape There

is also less chance of error The same principle applies to reinforcing bars embedded

plates etc

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6 Be aware of material limitations

Examples of this are the radius requirements for bending reinforcing bars standard

lengths for

certain sizes of inserts etc

7 Avoid non-standard tolerances

Dimensional tolerances which are specified to be more rigid than industry

standards are difficult to achieve Connections which require close-fitting parts without

provision for adjustment should be avoided as much as possible

8 Allow alternatives

Very often precasters will prefer certain details The producer should be allowed

to use alternative methods or materials provided the design requirements are met

Allowing alternative solutions willoften result in the most economical and best

performing connections

Considerations for transportation

During transportation any units protruding from the concrete element must be

shielded in order not to create a hazard to people Protruding units must be able to

withstand any shocks they can be subjected to during handling Protruding units like

reinforcing bars can in many cases be difficult to handle during transportation For

example a wall panel shall be transported standing at the edge but has reinforcing bars

protruding at the bottom This will make it necessary to build up the support on the

trucks which is costly takes time and makes the load less stable This problem can be

solved by letting the bars protrude from the top of the element but then the total height

may make it difficult to negotiate the underpasses en route The solution may then be to

have the protruding bars replaced by insert and threaded bar to screw in after the element

has been transported to the site

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If protruding units do not create the kind of problems described above because

they do not stick out that much there still may be some difficulties For example corbels

pointing down during transport may necessitate a lot of additional support provisions for

the columns on the trucks The consequence can be a less stable load or decreased

loading capacity of the truck This kind of problem can be solved by making columns

with the corbels in one plane only and then place every second column lsquotop-to-bottomrsquo

on the trucks Otherwise it is also possible to look for a corbel-free solution

Considerations for Erection

To fully realise this benefit of fast erection of a precast structure and to keep the

costs within reasonable limits field connections should be kept simple In order to fulfil

the design requirements it is sometimes necessary to compromise fabrication and

erection simplicity

1 Use connections that are not weather sensitive

Materials such as grout dry pack cast-in-place concrete and epoxies need special

provisions to be placed in cold weather Welding is slower when the ambient temperature

is low If the connections are designed so that these processes must be completed before

erection can continue costly delays may result

2 Stability of the elements

Some elements may require propping shoring bracing or fastening before the

hoist can be unhooked Planning for the fewest quickest and safest possible operations to

be executed before releasing the hoist will greatly facilitate the erection

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3 Stability of the structure

In every stage of the erection process the stability of the structure as a whole must

be planned and assured If not costly additional measures may have to be taken The

type of connection used may play a decisive role in this

4 Be aware of possible different loading conditions during erection

During erection loading conditions can occur which induce stresses or

deformations as well in the precast concrete units as in the connections which are higher

than those under service conditions When designing the connections due consideration

has to be paid to these effects unless special measures are taken during the erection such

as temporary supports etc to prevent such situations

5 Standardize connection types

All connections which serve similar functions within the building should be

standardized as much as possible As workmen become familiar with the procedures

required to make the connection productivity is enhanced and there is less chance for

error

Some types of connections require skilled craftsmen to accomplish for example

welding and post tensioning The fewer of these skilled trades required the more

economical the connection will be

6 Standardize sizes of components

Whenever possible such things as field bolts loose angles etc should be of

common size for all connections This reduces the chance for error and the time required

searching for the proper item

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7 Use connections that are not susceptible to damage in handling

Reinforcing bars steel plates dowels and bolts that project from the precast piece

will often be damaged in handling requiring repair to make them fit especially if they

are of small diameter or thickness

Connection detail that makes erection impossible

Support solution that makes erection impossible

SHEAR WALL

Shear walls are vertical elements of the horizontal force resisting system Shear walls are

constructed to counter the effects of lateral load acting on a structure In residential

construction shear walls are straight external walls that typically form a box which

provides all of the lateral support for the building

Importance of shear wall

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When shear walls are designed and constructed property and they will have the strength

and stiffness to resist the horizontal forces In building construction a rigid vertical

diaphragm capable of transferring lateral forces from exterior walls floors and roofs to

the ground foundation in a direction parallel to their planes Lateral forces caused by

wind earthquake and uneven settlement loads In addition to the weight of structure and

occupants create powerful twisting (torsion) forces These forces can literally tear (shear)

a building apart Reinforcing a frame by attaching or placing a rigid wall inside it

maintains that shape of the frame and prevents rotation at the joints shear walls are

especially important in high-rise building subjected to lateral wind and seismic forces

In the last two decades shear walls became an important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structure are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at those floors

Purpose of constructing shear walls

1 Shear walls are not only designed to resist gravityvertical loads due to its self weight

amp other living moving loads) but they are also designed for lateral loads of

earthquakeswind The walls are structurally integrated with roofsfloors (diaphragms)

and other lateral

2Shear wall structural systems are more stable because their supporting area (Total

cross sectional area of all shear walls) with reference to total plans area of building is

comparatively more unlike in the case of RCC framed structures

3 Walls have to resist the uplift forces caused by the pull of the wind walls have to

resist the shear forces that try to push the walls over walls have to resist the lateral force

of the wind that tries to push the walls in and pull them away from the building

4 Walls floors and roofs to the ground foundation in a direction parallel to their planes

Lateral forces caused by wind earthquake and uneven settlement loads In addition to the

weight of structure and occupants create powerful twisting (torsion) forces These forces

can literally tear (shear) a building apart Reinforcing a frame by attaching or placing a

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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Unit-1

Design principles

Prefabrication is the practice of assembling components of a structure in

a factory or other manufacturing site and transporting complete assemblies or sub-

assemblies to the construction site where the structure is to be located The term is used

to distinguish this process from the more conventional construction practice of

transporting the basic materials to the construction site where all assembly is carried out

Prefabrication is one of the architectural constructions Large units of a building are

produced in factories to be assembled ready-made on the building site This technique

permits the speedy erection of very large structures Units may include doors stairs

windows wall panels floor panels roof trusses and even entire buildings

Prefabricated building

Prefabricated building is a type of building that consists of several factory-built

components or units that are assembled on-site to complete the unit

The term prefabricated is buildings built in components (eg panels) modules (modular

homes) transportable sections (manufactured homes)It may also be used to refer to

mobile homes

Different Between Prefabricated Constructions and Conventional Type

The conventional method of building a house is to transport bricks timber

cement sand and construction aggregate etc to the site and to construct the house on

site from these materials In prefabricated construction only the foundations and floor

slabs are constructed in this way while sections of walls and roof are prefabricated

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(assembled) in a factory (possibly with window and door frames included) transported to

the site lifted into place by a crane and bolted together

Need for Prefabrication

Cost of construction

shorter construction time

easy of expansion

utilization of material

attractive finishes

highly efficient for weather resistance

single source assurance

insurance advantage

Material Properties In of Prefabricated Structures

Quick to assemble

Cost-effective

Portablemovable

Strong

Waterproof Moisture proof

Fire Resistant

Prefabrication Types

1 Conventional prefabrication construction is the most traditional construction

method where all the construction activities are in-situ practices on site

2 Semi-prefabrication divides as two sub-categories system formwork and non-

structural semi-prefabrication involving a part of in-situ construction activities

and a part of prefabrication Normally the non-structural semi-prefabrication is

applied on faccedilade curtain walls lost form systems and dry wall systems

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3 Comprehensive prefabrication involves a structural part and pre-finished

construction Examples of applications of structural comprehensive prefabrication

include staircases slabs columns and beams and

4 Volumetric off-site fabrication encloses usable space but does not constitute the

whole building Volumetric off-site fabrication is mainly used for lsquofacilitiesrsquo and

includes solutions on office washrooms plant rooms building services risers and

lifts

ADVANTAGES OF PREFABRICATION

1 Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

2 Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

3 Quality control can be easier in a factory assembly line setting than a construction

site setting

4 Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

5 Time spent in bad weather or hazardous environments at the construction site is

minimized

6 Less waste may be generated and in a factory setting it may be easier to recycle it

back into the manufacturing process for instance it is less costly to recycle scrap

metal generated in a metal fabrication shop than on the construction site

7 On-site construction and congestion is minimized

DISADVANTAGES OF PREFABRICATION

1 Careful handling of prefabricated components such as concrete panels or steel and

glass panels is required

2 Attention has to be paid to the strength and corrosion-resistance of the joining of

prefabricated sections to avoid failure of the joint

3 Similarly leaks can form at joints in prefabricated components

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4 Transportation costs may be higher for voluminous prefabricated sections than for

the materials of which they are made which can often be packed more compactly

5 Large prefabricated sections require heavy-duty cranes and precision measurement

and handling to place in position

6 Modular coordination

7 Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit or basic module known as 1M that equals to 100

mm The use of MC is an important factor in IBS effective application as it

completes the industry through quality control and increase of productivity

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MODULAR HOMES

Modular homes are houses divided into multiple modules sections which are

manufactured in a remote facility and then delivered to their intended site of use The

modules are assembled into a single residential building using either a crane or trucks

Steel andor wood framing are common options for building a modular homes Modular

components are typically constructed within a large indoor facility on assembly lines

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Modular homes

Indoor Construction of modular homes

Such dwellings are often priced lower than their site-built counterparts and are typically

more cost-effective to builders and consumers These new homes can be constructed in

less time than it takes to build a home on-siteldquo

Importance of modular homes

1 Indoor construction Assembly is independent of weather which increases work

efficiency and avoids damaged building material

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2 Favourable pricing from suppliers Large-scale manufacturers can effectively

bargain with suppliers for discounts on materials

3 Ability to service remote locations Particularly in countries such as Australia

there can be much higher costs to build a site-built house in a remote area or an

area experiencing a construction boom such as mining towns Modular homes can

be built in major towns and sold to regional areas

4 Low waste With the same plans being constantly built the manufacturer has

records of exactly what quantity of materials is needed for a given job While

waste from a site-built dwelling may typically fill several large dumpsters waste

from a modular dwelling generates much less waste

5 Building Strength According to manufacturers modular homes are generally

designed to be initially stronger than traditional homesFor example replacing

nails with screws and adding glue to joints This is supposed to help the modules

maintain their structural integrity as they are transported on trucks to the

construction site

6 Assembly Time The modules that will combine to form the house are assembled

off-site in a factory These modules can take one to three months to be constructed

but often take as little as 10 days to actually construct when they are first started

Then they are transported to the building site where a crane is brought in to

assemble the modules togetherThe placement of the modules together generally

takes several hours or days

Mobile Homes

Mobile homes or static caravans are prefabricated homes built in factories rather than on

site and then taken to the place where they will be occupied They are usually

transported by tractor-trailers over public roads to sites which are often in rural areas or

high-density developments In some countries they are used for temporary

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accommodation on campsites While these houses are usually placed in one location and

left there permanently or they have the ability to be move

Behind the work fitted at installation to hide the base there are strong trailer frames

axles wheels and tow-hitches The two major sizes are single-wides and double-wides

1 Single-wides are eighteen feet or less in width and 90 feet (27 m) or less in length

and can be towed to their site as a single unit

Double-wides are twenty feet or more wide and are 90 feet (27 m) in length or less and

are towed to their site in two separate units which are then joined together

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Mobile homes

Production Transportation and Erection

Considerations in production

The general rule is that the connection device must be as lsquofoolproofrsquo as possible It

should be possible to place it in the mould correctly oriented and within the necessary

tolerances with a minimum of effort

1 Avoid congestion

At the location of connections additional reinforcing steel embedded plates

inserts block-outs etc are frequently required It is not unusual that so many items are

concentrated in a small location that very little room is left for the concrete It must be

kept in mind that reinforcing bars and prestressing strands which appear as lines on the

drawing take up real space in the elements Reinforcing bars require more space than

their nominal diameter and there must be room for the curvature of bent bars If

congestion is suspected it is helpful to draw large-scale details of the region in question

2 Avoid penetration of the forms

Units requiring holes in the forms should be avoided if possible especially in steel

moulds Exceptions to this rule can be made if there is a substantial amount of repetition

in the production Holes in the forms may be necessary not only because the units are

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protruding from the elements but also for the arrangement used to keep the units in place

during casting The units must also be designed so that they do not make the dismantling

of the form impossible without damage to the form Most forms are supposed to be used

more than once Connection units to be placed in the top surface during casting should be

secured against the edges of the mould using purpose made holding devices These

devices are mostly costly make it more difficult to obtain a smooth surface or the

holding device may hamper the placement of concrete or other surface material The

various disadvantages have to be evaluated before selecting the method However if the

same steel plate is placed in the bottom of the form it can be located with great accuracy

as it can be fixed to the bottom directly

3 Reduce post-stripping work

A plant casting operation is most efficient when the product can be taken directly

to the storage area immediately after removal from the form Any operations required

after stripping and before erection such as special cleaning or finishing welding on

projecting hardware etc should be avoided These operations require additional handling

(increased possibility of damage to the elements) extra workspace and added labour

often with skilled trades Sometimes a trade-off is necessary between penetration of the

forms and post-stripping work

4 Use repetitious details

It is very desirable to repeat details as much as possible Similar details should be

identical even ifit results in a slight over-design

5 Use standard items

Hardware items such as inserts studs steel elements etc should be readily

available standard items that are preferably from more than one supplier It also

simplifies fabrication if similar product items are standardised as to size and shape There

is also less chance of error The same principle applies to reinforcing bars embedded

plates etc

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6 Be aware of material limitations

Examples of this are the radius requirements for bending reinforcing bars standard

lengths for

certain sizes of inserts etc

7 Avoid non-standard tolerances

Dimensional tolerances which are specified to be more rigid than industry

standards are difficult to achieve Connections which require close-fitting parts without

provision for adjustment should be avoided as much as possible

8 Allow alternatives

Very often precasters will prefer certain details The producer should be allowed

to use alternative methods or materials provided the design requirements are met

Allowing alternative solutions willoften result in the most economical and best

performing connections

Considerations for transportation

During transportation any units protruding from the concrete element must be

shielded in order not to create a hazard to people Protruding units must be able to

withstand any shocks they can be subjected to during handling Protruding units like

reinforcing bars can in many cases be difficult to handle during transportation For

example a wall panel shall be transported standing at the edge but has reinforcing bars

protruding at the bottom This will make it necessary to build up the support on the

trucks which is costly takes time and makes the load less stable This problem can be

solved by letting the bars protrude from the top of the element but then the total height

may make it difficult to negotiate the underpasses en route The solution may then be to

have the protruding bars replaced by insert and threaded bar to screw in after the element

has been transported to the site

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If protruding units do not create the kind of problems described above because

they do not stick out that much there still may be some difficulties For example corbels

pointing down during transport may necessitate a lot of additional support provisions for

the columns on the trucks The consequence can be a less stable load or decreased

loading capacity of the truck This kind of problem can be solved by making columns

with the corbels in one plane only and then place every second column lsquotop-to-bottomrsquo

on the trucks Otherwise it is also possible to look for a corbel-free solution

Considerations for Erection

To fully realise this benefit of fast erection of a precast structure and to keep the

costs within reasonable limits field connections should be kept simple In order to fulfil

the design requirements it is sometimes necessary to compromise fabrication and

erection simplicity

1 Use connections that are not weather sensitive

Materials such as grout dry pack cast-in-place concrete and epoxies need special

provisions to be placed in cold weather Welding is slower when the ambient temperature

is low If the connections are designed so that these processes must be completed before

erection can continue costly delays may result

2 Stability of the elements

Some elements may require propping shoring bracing or fastening before the

hoist can be unhooked Planning for the fewest quickest and safest possible operations to

be executed before releasing the hoist will greatly facilitate the erection

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3 Stability of the structure

In every stage of the erection process the stability of the structure as a whole must

be planned and assured If not costly additional measures may have to be taken The

type of connection used may play a decisive role in this

4 Be aware of possible different loading conditions during erection

During erection loading conditions can occur which induce stresses or

deformations as well in the precast concrete units as in the connections which are higher

than those under service conditions When designing the connections due consideration

has to be paid to these effects unless special measures are taken during the erection such

as temporary supports etc to prevent such situations

5 Standardize connection types

All connections which serve similar functions within the building should be

standardized as much as possible As workmen become familiar with the procedures

required to make the connection productivity is enhanced and there is less chance for

error

Some types of connections require skilled craftsmen to accomplish for example

welding and post tensioning The fewer of these skilled trades required the more

economical the connection will be

6 Standardize sizes of components

Whenever possible such things as field bolts loose angles etc should be of

common size for all connections This reduces the chance for error and the time required

searching for the proper item

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7 Use connections that are not susceptible to damage in handling

Reinforcing bars steel plates dowels and bolts that project from the precast piece

will often be damaged in handling requiring repair to make them fit especially if they

are of small diameter or thickness

Connection detail that makes erection impossible

Support solution that makes erection impossible

SHEAR WALL

Shear walls are vertical elements of the horizontal force resisting system Shear walls are

constructed to counter the effects of lateral load acting on a structure In residential

construction shear walls are straight external walls that typically form a box which

provides all of the lateral support for the building

Importance of shear wall

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When shear walls are designed and constructed property and they will have the strength

and stiffness to resist the horizontal forces In building construction a rigid vertical

diaphragm capable of transferring lateral forces from exterior walls floors and roofs to

the ground foundation in a direction parallel to their planes Lateral forces caused by

wind earthquake and uneven settlement loads In addition to the weight of structure and

occupants create powerful twisting (torsion) forces These forces can literally tear (shear)

a building apart Reinforcing a frame by attaching or placing a rigid wall inside it

maintains that shape of the frame and prevents rotation at the joints shear walls are

especially important in high-rise building subjected to lateral wind and seismic forces

In the last two decades shear walls became an important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structure are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at those floors

Purpose of constructing shear walls

1 Shear walls are not only designed to resist gravityvertical loads due to its self weight

amp other living moving loads) but they are also designed for lateral loads of

earthquakeswind The walls are structurally integrated with roofsfloors (diaphragms)

and other lateral

2Shear wall structural systems are more stable because their supporting area (Total

cross sectional area of all shear walls) with reference to total plans area of building is

comparatively more unlike in the case of RCC framed structures

3 Walls have to resist the uplift forces caused by the pull of the wind walls have to

resist the shear forces that try to push the walls over walls have to resist the lateral force

of the wind that tries to push the walls in and pull them away from the building

4 Walls floors and roofs to the ground foundation in a direction parallel to their planes

Lateral forces caused by wind earthquake and uneven settlement loads In addition to the

weight of structure and occupants create powerful twisting (torsion) forces These forces

can literally tear (shear) a building apart Reinforcing a frame by attaching or placing a

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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(assembled) in a factory (possibly with window and door frames included) transported to

the site lifted into place by a crane and bolted together

Need for Prefabrication

Cost of construction

shorter construction time

easy of expansion

utilization of material

attractive finishes

highly efficient for weather resistance

single source assurance

insurance advantage

Material Properties In of Prefabricated Structures

Quick to assemble

Cost-effective

Portablemovable

Strong

Waterproof Moisture proof

Fire Resistant

Prefabrication Types

1 Conventional prefabrication construction is the most traditional construction

method where all the construction activities are in-situ practices on site

2 Semi-prefabrication divides as two sub-categories system formwork and non-

structural semi-prefabrication involving a part of in-situ construction activities

and a part of prefabrication Normally the non-structural semi-prefabrication is

applied on faccedilade curtain walls lost form systems and dry wall systems

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3 Comprehensive prefabrication involves a structural part and pre-finished

construction Examples of applications of structural comprehensive prefabrication

include staircases slabs columns and beams and

4 Volumetric off-site fabrication encloses usable space but does not constitute the

whole building Volumetric off-site fabrication is mainly used for lsquofacilitiesrsquo and

includes solutions on office washrooms plant rooms building services risers and

lifts

ADVANTAGES OF PREFABRICATION

1 Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

2 Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

3 Quality control can be easier in a factory assembly line setting than a construction

site setting

4 Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

5 Time spent in bad weather or hazardous environments at the construction site is

minimized

6 Less waste may be generated and in a factory setting it may be easier to recycle it

back into the manufacturing process for instance it is less costly to recycle scrap

metal generated in a metal fabrication shop than on the construction site

7 On-site construction and congestion is minimized

DISADVANTAGES OF PREFABRICATION

1 Careful handling of prefabricated components such as concrete panels or steel and

glass panels is required

2 Attention has to be paid to the strength and corrosion-resistance of the joining of

prefabricated sections to avoid failure of the joint

3 Similarly leaks can form at joints in prefabricated components

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4 Transportation costs may be higher for voluminous prefabricated sections than for

the materials of which they are made which can often be packed more compactly

5 Large prefabricated sections require heavy-duty cranes and precision measurement

and handling to place in position

6 Modular coordination

7 Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit or basic module known as 1M that equals to 100

mm The use of MC is an important factor in IBS effective application as it

completes the industry through quality control and increase of productivity

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MODULAR HOMES

Modular homes are houses divided into multiple modules sections which are

manufactured in a remote facility and then delivered to their intended site of use The

modules are assembled into a single residential building using either a crane or trucks

Steel andor wood framing are common options for building a modular homes Modular

components are typically constructed within a large indoor facility on assembly lines

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Modular homes

Indoor Construction of modular homes

Such dwellings are often priced lower than their site-built counterparts and are typically

more cost-effective to builders and consumers These new homes can be constructed in

less time than it takes to build a home on-siteldquo

Importance of modular homes

1 Indoor construction Assembly is independent of weather which increases work

efficiency and avoids damaged building material

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2 Favourable pricing from suppliers Large-scale manufacturers can effectively

bargain with suppliers for discounts on materials

3 Ability to service remote locations Particularly in countries such as Australia

there can be much higher costs to build a site-built house in a remote area or an

area experiencing a construction boom such as mining towns Modular homes can

be built in major towns and sold to regional areas

4 Low waste With the same plans being constantly built the manufacturer has

records of exactly what quantity of materials is needed for a given job While

waste from a site-built dwelling may typically fill several large dumpsters waste

from a modular dwelling generates much less waste

5 Building Strength According to manufacturers modular homes are generally

designed to be initially stronger than traditional homesFor example replacing

nails with screws and adding glue to joints This is supposed to help the modules

maintain their structural integrity as they are transported on trucks to the

construction site

6 Assembly Time The modules that will combine to form the house are assembled

off-site in a factory These modules can take one to three months to be constructed

but often take as little as 10 days to actually construct when they are first started

Then they are transported to the building site where a crane is brought in to

assemble the modules togetherThe placement of the modules together generally

takes several hours or days

Mobile Homes

Mobile homes or static caravans are prefabricated homes built in factories rather than on

site and then taken to the place where they will be occupied They are usually

transported by tractor-trailers over public roads to sites which are often in rural areas or

high-density developments In some countries they are used for temporary

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accommodation on campsites While these houses are usually placed in one location and

left there permanently or they have the ability to be move

Behind the work fitted at installation to hide the base there are strong trailer frames

axles wheels and tow-hitches The two major sizes are single-wides and double-wides

1 Single-wides are eighteen feet or less in width and 90 feet (27 m) or less in length

and can be towed to their site as a single unit

Double-wides are twenty feet or more wide and are 90 feet (27 m) in length or less and

are towed to their site in two separate units which are then joined together

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Mobile homes

Production Transportation and Erection

Considerations in production

The general rule is that the connection device must be as lsquofoolproofrsquo as possible It

should be possible to place it in the mould correctly oriented and within the necessary

tolerances with a minimum of effort

1 Avoid congestion

At the location of connections additional reinforcing steel embedded plates

inserts block-outs etc are frequently required It is not unusual that so many items are

concentrated in a small location that very little room is left for the concrete It must be

kept in mind that reinforcing bars and prestressing strands which appear as lines on the

drawing take up real space in the elements Reinforcing bars require more space than

their nominal diameter and there must be room for the curvature of bent bars If

congestion is suspected it is helpful to draw large-scale details of the region in question

2 Avoid penetration of the forms

Units requiring holes in the forms should be avoided if possible especially in steel

moulds Exceptions to this rule can be made if there is a substantial amount of repetition

in the production Holes in the forms may be necessary not only because the units are

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protruding from the elements but also for the arrangement used to keep the units in place

during casting The units must also be designed so that they do not make the dismantling

of the form impossible without damage to the form Most forms are supposed to be used

more than once Connection units to be placed in the top surface during casting should be

secured against the edges of the mould using purpose made holding devices These

devices are mostly costly make it more difficult to obtain a smooth surface or the

holding device may hamper the placement of concrete or other surface material The

various disadvantages have to be evaluated before selecting the method However if the

same steel plate is placed in the bottom of the form it can be located with great accuracy

as it can be fixed to the bottom directly

3 Reduce post-stripping work

A plant casting operation is most efficient when the product can be taken directly

to the storage area immediately after removal from the form Any operations required

after stripping and before erection such as special cleaning or finishing welding on

projecting hardware etc should be avoided These operations require additional handling

(increased possibility of damage to the elements) extra workspace and added labour

often with skilled trades Sometimes a trade-off is necessary between penetration of the

forms and post-stripping work

4 Use repetitious details

It is very desirable to repeat details as much as possible Similar details should be

identical even ifit results in a slight over-design

5 Use standard items

Hardware items such as inserts studs steel elements etc should be readily

available standard items that are preferably from more than one supplier It also

simplifies fabrication if similar product items are standardised as to size and shape There

is also less chance of error The same principle applies to reinforcing bars embedded

plates etc

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6 Be aware of material limitations

Examples of this are the radius requirements for bending reinforcing bars standard

lengths for

certain sizes of inserts etc

7 Avoid non-standard tolerances

Dimensional tolerances which are specified to be more rigid than industry

standards are difficult to achieve Connections which require close-fitting parts without

provision for adjustment should be avoided as much as possible

8 Allow alternatives

Very often precasters will prefer certain details The producer should be allowed

to use alternative methods or materials provided the design requirements are met

Allowing alternative solutions willoften result in the most economical and best

performing connections

Considerations for transportation

During transportation any units protruding from the concrete element must be

shielded in order not to create a hazard to people Protruding units must be able to

withstand any shocks they can be subjected to during handling Protruding units like

reinforcing bars can in many cases be difficult to handle during transportation For

example a wall panel shall be transported standing at the edge but has reinforcing bars

protruding at the bottom This will make it necessary to build up the support on the

trucks which is costly takes time and makes the load less stable This problem can be

solved by letting the bars protrude from the top of the element but then the total height

may make it difficult to negotiate the underpasses en route The solution may then be to

have the protruding bars replaced by insert and threaded bar to screw in after the element

has been transported to the site

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If protruding units do not create the kind of problems described above because

they do not stick out that much there still may be some difficulties For example corbels

pointing down during transport may necessitate a lot of additional support provisions for

the columns on the trucks The consequence can be a less stable load or decreased

loading capacity of the truck This kind of problem can be solved by making columns

with the corbels in one plane only and then place every second column lsquotop-to-bottomrsquo

on the trucks Otherwise it is also possible to look for a corbel-free solution

Considerations for Erection

To fully realise this benefit of fast erection of a precast structure and to keep the

costs within reasonable limits field connections should be kept simple In order to fulfil

the design requirements it is sometimes necessary to compromise fabrication and

erection simplicity

1 Use connections that are not weather sensitive

Materials such as grout dry pack cast-in-place concrete and epoxies need special

provisions to be placed in cold weather Welding is slower when the ambient temperature

is low If the connections are designed so that these processes must be completed before

erection can continue costly delays may result

2 Stability of the elements

Some elements may require propping shoring bracing or fastening before the

hoist can be unhooked Planning for the fewest quickest and safest possible operations to

be executed before releasing the hoist will greatly facilitate the erection

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3 Stability of the structure

In every stage of the erection process the stability of the structure as a whole must

be planned and assured If not costly additional measures may have to be taken The

type of connection used may play a decisive role in this

4 Be aware of possible different loading conditions during erection

During erection loading conditions can occur which induce stresses or

deformations as well in the precast concrete units as in the connections which are higher

than those under service conditions When designing the connections due consideration

has to be paid to these effects unless special measures are taken during the erection such

as temporary supports etc to prevent such situations

5 Standardize connection types

All connections which serve similar functions within the building should be

standardized as much as possible As workmen become familiar with the procedures

required to make the connection productivity is enhanced and there is less chance for

error

Some types of connections require skilled craftsmen to accomplish for example

welding and post tensioning The fewer of these skilled trades required the more

economical the connection will be

6 Standardize sizes of components

Whenever possible such things as field bolts loose angles etc should be of

common size for all connections This reduces the chance for error and the time required

searching for the proper item

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7 Use connections that are not susceptible to damage in handling

Reinforcing bars steel plates dowels and bolts that project from the precast piece

will often be damaged in handling requiring repair to make them fit especially if they

are of small diameter or thickness

Connection detail that makes erection impossible

Support solution that makes erection impossible

SHEAR WALL

Shear walls are vertical elements of the horizontal force resisting system Shear walls are

constructed to counter the effects of lateral load acting on a structure In residential

construction shear walls are straight external walls that typically form a box which

provides all of the lateral support for the building

Importance of shear wall

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When shear walls are designed and constructed property and they will have the strength

and stiffness to resist the horizontal forces In building construction a rigid vertical

diaphragm capable of transferring lateral forces from exterior walls floors and roofs to

the ground foundation in a direction parallel to their planes Lateral forces caused by

wind earthquake and uneven settlement loads In addition to the weight of structure and

occupants create powerful twisting (torsion) forces These forces can literally tear (shear)

a building apart Reinforcing a frame by attaching or placing a rigid wall inside it

maintains that shape of the frame and prevents rotation at the joints shear walls are

especially important in high-rise building subjected to lateral wind and seismic forces

In the last two decades shear walls became an important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structure are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at those floors

Purpose of constructing shear walls

1 Shear walls are not only designed to resist gravityvertical loads due to its self weight

amp other living moving loads) but they are also designed for lateral loads of

earthquakeswind The walls are structurally integrated with roofsfloors (diaphragms)

and other lateral

2Shear wall structural systems are more stable because their supporting area (Total

cross sectional area of all shear walls) with reference to total plans area of building is

comparatively more unlike in the case of RCC framed structures

3 Walls have to resist the uplift forces caused by the pull of the wind walls have to

resist the shear forces that try to push the walls over walls have to resist the lateral force

of the wind that tries to push the walls in and pull them away from the building

4 Walls floors and roofs to the ground foundation in a direction parallel to their planes

Lateral forces caused by wind earthquake and uneven settlement loads In addition to the

weight of structure and occupants create powerful twisting (torsion) forces These forces

can literally tear (shear) a building apart Reinforcing a frame by attaching or placing a

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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3 Comprehensive prefabrication involves a structural part and pre-finished

construction Examples of applications of structural comprehensive prefabrication

include staircases slabs columns and beams and

4 Volumetric off-site fabrication encloses usable space but does not constitute the

whole building Volumetric off-site fabrication is mainly used for lsquofacilitiesrsquo and

includes solutions on office washrooms plant rooms building services risers and

lifts

ADVANTAGES OF PREFABRICATION

1 Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

2 Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

3 Quality control can be easier in a factory assembly line setting than a construction

site setting

4 Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

5 Time spent in bad weather or hazardous environments at the construction site is

minimized

6 Less waste may be generated and in a factory setting it may be easier to recycle it

back into the manufacturing process for instance it is less costly to recycle scrap

metal generated in a metal fabrication shop than on the construction site

7 On-site construction and congestion is minimized

DISADVANTAGES OF PREFABRICATION

1 Careful handling of prefabricated components such as concrete panels or steel and

glass panels is required

2 Attention has to be paid to the strength and corrosion-resistance of the joining of

prefabricated sections to avoid failure of the joint

3 Similarly leaks can form at joints in prefabricated components

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4 Transportation costs may be higher for voluminous prefabricated sections than for

the materials of which they are made which can often be packed more compactly

5 Large prefabricated sections require heavy-duty cranes and precision measurement

and handling to place in position

6 Modular coordination

7 Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit or basic module known as 1M that equals to 100

mm The use of MC is an important factor in IBS effective application as it

completes the industry through quality control and increase of productivity

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MODULAR HOMES

Modular homes are houses divided into multiple modules sections which are

manufactured in a remote facility and then delivered to their intended site of use The

modules are assembled into a single residential building using either a crane or trucks

Steel andor wood framing are common options for building a modular homes Modular

components are typically constructed within a large indoor facility on assembly lines

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Modular homes

Indoor Construction of modular homes

Such dwellings are often priced lower than their site-built counterparts and are typically

more cost-effective to builders and consumers These new homes can be constructed in

less time than it takes to build a home on-siteldquo

Importance of modular homes

1 Indoor construction Assembly is independent of weather which increases work

efficiency and avoids damaged building material

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2 Favourable pricing from suppliers Large-scale manufacturers can effectively

bargain with suppliers for discounts on materials

3 Ability to service remote locations Particularly in countries such as Australia

there can be much higher costs to build a site-built house in a remote area or an

area experiencing a construction boom such as mining towns Modular homes can

be built in major towns and sold to regional areas

4 Low waste With the same plans being constantly built the manufacturer has

records of exactly what quantity of materials is needed for a given job While

waste from a site-built dwelling may typically fill several large dumpsters waste

from a modular dwelling generates much less waste

5 Building Strength According to manufacturers modular homes are generally

designed to be initially stronger than traditional homesFor example replacing

nails with screws and adding glue to joints This is supposed to help the modules

maintain their structural integrity as they are transported on trucks to the

construction site

6 Assembly Time The modules that will combine to form the house are assembled

off-site in a factory These modules can take one to three months to be constructed

but often take as little as 10 days to actually construct when they are first started

Then they are transported to the building site where a crane is brought in to

assemble the modules togetherThe placement of the modules together generally

takes several hours or days

Mobile Homes

Mobile homes or static caravans are prefabricated homes built in factories rather than on

site and then taken to the place where they will be occupied They are usually

transported by tractor-trailers over public roads to sites which are often in rural areas or

high-density developments In some countries they are used for temporary

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accommodation on campsites While these houses are usually placed in one location and

left there permanently or they have the ability to be move

Behind the work fitted at installation to hide the base there are strong trailer frames

axles wheels and tow-hitches The two major sizes are single-wides and double-wides

1 Single-wides are eighteen feet or less in width and 90 feet (27 m) or less in length

and can be towed to their site as a single unit

Double-wides are twenty feet or more wide and are 90 feet (27 m) in length or less and

are towed to their site in two separate units which are then joined together

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Mobile homes

Production Transportation and Erection

Considerations in production

The general rule is that the connection device must be as lsquofoolproofrsquo as possible It

should be possible to place it in the mould correctly oriented and within the necessary

tolerances with a minimum of effort

1 Avoid congestion

At the location of connections additional reinforcing steel embedded plates

inserts block-outs etc are frequently required It is not unusual that so many items are

concentrated in a small location that very little room is left for the concrete It must be

kept in mind that reinforcing bars and prestressing strands which appear as lines on the

drawing take up real space in the elements Reinforcing bars require more space than

their nominal diameter and there must be room for the curvature of bent bars If

congestion is suspected it is helpful to draw large-scale details of the region in question

2 Avoid penetration of the forms

Units requiring holes in the forms should be avoided if possible especially in steel

moulds Exceptions to this rule can be made if there is a substantial amount of repetition

in the production Holes in the forms may be necessary not only because the units are

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protruding from the elements but also for the arrangement used to keep the units in place

during casting The units must also be designed so that they do not make the dismantling

of the form impossible without damage to the form Most forms are supposed to be used

more than once Connection units to be placed in the top surface during casting should be

secured against the edges of the mould using purpose made holding devices These

devices are mostly costly make it more difficult to obtain a smooth surface or the

holding device may hamper the placement of concrete or other surface material The

various disadvantages have to be evaluated before selecting the method However if the

same steel plate is placed in the bottom of the form it can be located with great accuracy

as it can be fixed to the bottom directly

3 Reduce post-stripping work

A plant casting operation is most efficient when the product can be taken directly

to the storage area immediately after removal from the form Any operations required

after stripping and before erection such as special cleaning or finishing welding on

projecting hardware etc should be avoided These operations require additional handling

(increased possibility of damage to the elements) extra workspace and added labour

often with skilled trades Sometimes a trade-off is necessary between penetration of the

forms and post-stripping work

4 Use repetitious details

It is very desirable to repeat details as much as possible Similar details should be

identical even ifit results in a slight over-design

5 Use standard items

Hardware items such as inserts studs steel elements etc should be readily

available standard items that are preferably from more than one supplier It also

simplifies fabrication if similar product items are standardised as to size and shape There

is also less chance of error The same principle applies to reinforcing bars embedded

plates etc

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6 Be aware of material limitations

Examples of this are the radius requirements for bending reinforcing bars standard

lengths for

certain sizes of inserts etc

7 Avoid non-standard tolerances

Dimensional tolerances which are specified to be more rigid than industry

standards are difficult to achieve Connections which require close-fitting parts without

provision for adjustment should be avoided as much as possible

8 Allow alternatives

Very often precasters will prefer certain details The producer should be allowed

to use alternative methods or materials provided the design requirements are met

Allowing alternative solutions willoften result in the most economical and best

performing connections

Considerations for transportation

During transportation any units protruding from the concrete element must be

shielded in order not to create a hazard to people Protruding units must be able to

withstand any shocks they can be subjected to during handling Protruding units like

reinforcing bars can in many cases be difficult to handle during transportation For

example a wall panel shall be transported standing at the edge but has reinforcing bars

protruding at the bottom This will make it necessary to build up the support on the

trucks which is costly takes time and makes the load less stable This problem can be

solved by letting the bars protrude from the top of the element but then the total height

may make it difficult to negotiate the underpasses en route The solution may then be to

have the protruding bars replaced by insert and threaded bar to screw in after the element

has been transported to the site

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If protruding units do not create the kind of problems described above because

they do not stick out that much there still may be some difficulties For example corbels

pointing down during transport may necessitate a lot of additional support provisions for

the columns on the trucks The consequence can be a less stable load or decreased

loading capacity of the truck This kind of problem can be solved by making columns

with the corbels in one plane only and then place every second column lsquotop-to-bottomrsquo

on the trucks Otherwise it is also possible to look for a corbel-free solution

Considerations for Erection

To fully realise this benefit of fast erection of a precast structure and to keep the

costs within reasonable limits field connections should be kept simple In order to fulfil

the design requirements it is sometimes necessary to compromise fabrication and

erection simplicity

1 Use connections that are not weather sensitive

Materials such as grout dry pack cast-in-place concrete and epoxies need special

provisions to be placed in cold weather Welding is slower when the ambient temperature

is low If the connections are designed so that these processes must be completed before

erection can continue costly delays may result

2 Stability of the elements

Some elements may require propping shoring bracing or fastening before the

hoist can be unhooked Planning for the fewest quickest and safest possible operations to

be executed before releasing the hoist will greatly facilitate the erection

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3 Stability of the structure

In every stage of the erection process the stability of the structure as a whole must

be planned and assured If not costly additional measures may have to be taken The

type of connection used may play a decisive role in this

4 Be aware of possible different loading conditions during erection

During erection loading conditions can occur which induce stresses or

deformations as well in the precast concrete units as in the connections which are higher

than those under service conditions When designing the connections due consideration

has to be paid to these effects unless special measures are taken during the erection such

as temporary supports etc to prevent such situations

5 Standardize connection types

All connections which serve similar functions within the building should be

standardized as much as possible As workmen become familiar with the procedures

required to make the connection productivity is enhanced and there is less chance for

error

Some types of connections require skilled craftsmen to accomplish for example

welding and post tensioning The fewer of these skilled trades required the more

economical the connection will be

6 Standardize sizes of components

Whenever possible such things as field bolts loose angles etc should be of

common size for all connections This reduces the chance for error and the time required

searching for the proper item

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7 Use connections that are not susceptible to damage in handling

Reinforcing bars steel plates dowels and bolts that project from the precast piece

will often be damaged in handling requiring repair to make them fit especially if they

are of small diameter or thickness

Connection detail that makes erection impossible

Support solution that makes erection impossible

SHEAR WALL

Shear walls are vertical elements of the horizontal force resisting system Shear walls are

constructed to counter the effects of lateral load acting on a structure In residential

construction shear walls are straight external walls that typically form a box which

provides all of the lateral support for the building

Importance of shear wall

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When shear walls are designed and constructed property and they will have the strength

and stiffness to resist the horizontal forces In building construction a rigid vertical

diaphragm capable of transferring lateral forces from exterior walls floors and roofs to

the ground foundation in a direction parallel to their planes Lateral forces caused by

wind earthquake and uneven settlement loads In addition to the weight of structure and

occupants create powerful twisting (torsion) forces These forces can literally tear (shear)

a building apart Reinforcing a frame by attaching or placing a rigid wall inside it

maintains that shape of the frame and prevents rotation at the joints shear walls are

especially important in high-rise building subjected to lateral wind and seismic forces

In the last two decades shear walls became an important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structure are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at those floors

Purpose of constructing shear walls

1 Shear walls are not only designed to resist gravityvertical loads due to its self weight

amp other living moving loads) but they are also designed for lateral loads of

earthquakeswind The walls are structurally integrated with roofsfloors (diaphragms)

and other lateral

2Shear wall structural systems are more stable because their supporting area (Total

cross sectional area of all shear walls) with reference to total plans area of building is

comparatively more unlike in the case of RCC framed structures

3 Walls have to resist the uplift forces caused by the pull of the wind walls have to

resist the shear forces that try to push the walls over walls have to resist the lateral force

of the wind that tries to push the walls in and pull them away from the building

4 Walls floors and roofs to the ground foundation in a direction parallel to their planes

Lateral forces caused by wind earthquake and uneven settlement loads In addition to the

weight of structure and occupants create powerful twisting (torsion) forces These forces

can literally tear (shear) a building apart Reinforcing a frame by attaching or placing a

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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4 Transportation costs may be higher for voluminous prefabricated sections than for

the materials of which they are made which can often be packed more compactly

5 Large prefabricated sections require heavy-duty cranes and precision measurement

and handling to place in position

6 Modular coordination

7 Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit or basic module known as 1M that equals to 100

mm The use of MC is an important factor in IBS effective application as it

completes the industry through quality control and increase of productivity

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MODULAR HOMES

Modular homes are houses divided into multiple modules sections which are

manufactured in a remote facility and then delivered to their intended site of use The

modules are assembled into a single residential building using either a crane or trucks

Steel andor wood framing are common options for building a modular homes Modular

components are typically constructed within a large indoor facility on assembly lines

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Modular homes

Indoor Construction of modular homes

Such dwellings are often priced lower than their site-built counterparts and are typically

more cost-effective to builders and consumers These new homes can be constructed in

less time than it takes to build a home on-siteldquo

Importance of modular homes

1 Indoor construction Assembly is independent of weather which increases work

efficiency and avoids damaged building material

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2 Favourable pricing from suppliers Large-scale manufacturers can effectively

bargain with suppliers for discounts on materials

3 Ability to service remote locations Particularly in countries such as Australia

there can be much higher costs to build a site-built house in a remote area or an

area experiencing a construction boom such as mining towns Modular homes can

be built in major towns and sold to regional areas

4 Low waste With the same plans being constantly built the manufacturer has

records of exactly what quantity of materials is needed for a given job While

waste from a site-built dwelling may typically fill several large dumpsters waste

from a modular dwelling generates much less waste

5 Building Strength According to manufacturers modular homes are generally

designed to be initially stronger than traditional homesFor example replacing

nails with screws and adding glue to joints This is supposed to help the modules

maintain their structural integrity as they are transported on trucks to the

construction site

6 Assembly Time The modules that will combine to form the house are assembled

off-site in a factory These modules can take one to three months to be constructed

but often take as little as 10 days to actually construct when they are first started

Then they are transported to the building site where a crane is brought in to

assemble the modules togetherThe placement of the modules together generally

takes several hours or days

Mobile Homes

Mobile homes or static caravans are prefabricated homes built in factories rather than on

site and then taken to the place where they will be occupied They are usually

transported by tractor-trailers over public roads to sites which are often in rural areas or

high-density developments In some countries they are used for temporary

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accommodation on campsites While these houses are usually placed in one location and

left there permanently or they have the ability to be move

Behind the work fitted at installation to hide the base there are strong trailer frames

axles wheels and tow-hitches The two major sizes are single-wides and double-wides

1 Single-wides are eighteen feet or less in width and 90 feet (27 m) or less in length

and can be towed to their site as a single unit

Double-wides are twenty feet or more wide and are 90 feet (27 m) in length or less and

are towed to their site in two separate units which are then joined together

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Mobile homes

Production Transportation and Erection

Considerations in production

The general rule is that the connection device must be as lsquofoolproofrsquo as possible It

should be possible to place it in the mould correctly oriented and within the necessary

tolerances with a minimum of effort

1 Avoid congestion

At the location of connections additional reinforcing steel embedded plates

inserts block-outs etc are frequently required It is not unusual that so many items are

concentrated in a small location that very little room is left for the concrete It must be

kept in mind that reinforcing bars and prestressing strands which appear as lines on the

drawing take up real space in the elements Reinforcing bars require more space than

their nominal diameter and there must be room for the curvature of bent bars If

congestion is suspected it is helpful to draw large-scale details of the region in question

2 Avoid penetration of the forms

Units requiring holes in the forms should be avoided if possible especially in steel

moulds Exceptions to this rule can be made if there is a substantial amount of repetition

in the production Holes in the forms may be necessary not only because the units are

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protruding from the elements but also for the arrangement used to keep the units in place

during casting The units must also be designed so that they do not make the dismantling

of the form impossible without damage to the form Most forms are supposed to be used

more than once Connection units to be placed in the top surface during casting should be

secured against the edges of the mould using purpose made holding devices These

devices are mostly costly make it more difficult to obtain a smooth surface or the

holding device may hamper the placement of concrete or other surface material The

various disadvantages have to be evaluated before selecting the method However if the

same steel plate is placed in the bottom of the form it can be located with great accuracy

as it can be fixed to the bottom directly

3 Reduce post-stripping work

A plant casting operation is most efficient when the product can be taken directly

to the storage area immediately after removal from the form Any operations required

after stripping and before erection such as special cleaning or finishing welding on

projecting hardware etc should be avoided These operations require additional handling

(increased possibility of damage to the elements) extra workspace and added labour

often with skilled trades Sometimes a trade-off is necessary between penetration of the

forms and post-stripping work

4 Use repetitious details

It is very desirable to repeat details as much as possible Similar details should be

identical even ifit results in a slight over-design

5 Use standard items

Hardware items such as inserts studs steel elements etc should be readily

available standard items that are preferably from more than one supplier It also

simplifies fabrication if similar product items are standardised as to size and shape There

is also less chance of error The same principle applies to reinforcing bars embedded

plates etc

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6 Be aware of material limitations

Examples of this are the radius requirements for bending reinforcing bars standard

lengths for

certain sizes of inserts etc

7 Avoid non-standard tolerances

Dimensional tolerances which are specified to be more rigid than industry

standards are difficult to achieve Connections which require close-fitting parts without

provision for adjustment should be avoided as much as possible

8 Allow alternatives

Very often precasters will prefer certain details The producer should be allowed

to use alternative methods or materials provided the design requirements are met

Allowing alternative solutions willoften result in the most economical and best

performing connections

Considerations for transportation

During transportation any units protruding from the concrete element must be

shielded in order not to create a hazard to people Protruding units must be able to

withstand any shocks they can be subjected to during handling Protruding units like

reinforcing bars can in many cases be difficult to handle during transportation For

example a wall panel shall be transported standing at the edge but has reinforcing bars

protruding at the bottom This will make it necessary to build up the support on the

trucks which is costly takes time and makes the load less stable This problem can be

solved by letting the bars protrude from the top of the element but then the total height

may make it difficult to negotiate the underpasses en route The solution may then be to

have the protruding bars replaced by insert and threaded bar to screw in after the element

has been transported to the site

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If protruding units do not create the kind of problems described above because

they do not stick out that much there still may be some difficulties For example corbels

pointing down during transport may necessitate a lot of additional support provisions for

the columns on the trucks The consequence can be a less stable load or decreased

loading capacity of the truck This kind of problem can be solved by making columns

with the corbels in one plane only and then place every second column lsquotop-to-bottomrsquo

on the trucks Otherwise it is also possible to look for a corbel-free solution

Considerations for Erection

To fully realise this benefit of fast erection of a precast structure and to keep the

costs within reasonable limits field connections should be kept simple In order to fulfil

the design requirements it is sometimes necessary to compromise fabrication and

erection simplicity

1 Use connections that are not weather sensitive

Materials such as grout dry pack cast-in-place concrete and epoxies need special

provisions to be placed in cold weather Welding is slower when the ambient temperature

is low If the connections are designed so that these processes must be completed before

erection can continue costly delays may result

2 Stability of the elements

Some elements may require propping shoring bracing or fastening before the

hoist can be unhooked Planning for the fewest quickest and safest possible operations to

be executed before releasing the hoist will greatly facilitate the erection

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3 Stability of the structure

In every stage of the erection process the stability of the structure as a whole must

be planned and assured If not costly additional measures may have to be taken The

type of connection used may play a decisive role in this

4 Be aware of possible different loading conditions during erection

During erection loading conditions can occur which induce stresses or

deformations as well in the precast concrete units as in the connections which are higher

than those under service conditions When designing the connections due consideration

has to be paid to these effects unless special measures are taken during the erection such

as temporary supports etc to prevent such situations

5 Standardize connection types

All connections which serve similar functions within the building should be

standardized as much as possible As workmen become familiar with the procedures

required to make the connection productivity is enhanced and there is less chance for

error

Some types of connections require skilled craftsmen to accomplish for example

welding and post tensioning The fewer of these skilled trades required the more

economical the connection will be

6 Standardize sizes of components

Whenever possible such things as field bolts loose angles etc should be of

common size for all connections This reduces the chance for error and the time required

searching for the proper item

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7 Use connections that are not susceptible to damage in handling

Reinforcing bars steel plates dowels and bolts that project from the precast piece

will often be damaged in handling requiring repair to make them fit especially if they

are of small diameter or thickness

Connection detail that makes erection impossible

Support solution that makes erection impossible

SHEAR WALL

Shear walls are vertical elements of the horizontal force resisting system Shear walls are

constructed to counter the effects of lateral load acting on a structure In residential

construction shear walls are straight external walls that typically form a box which

provides all of the lateral support for the building

Importance of shear wall

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When shear walls are designed and constructed property and they will have the strength

and stiffness to resist the horizontal forces In building construction a rigid vertical

diaphragm capable of transferring lateral forces from exterior walls floors and roofs to

the ground foundation in a direction parallel to their planes Lateral forces caused by

wind earthquake and uneven settlement loads In addition to the weight of structure and

occupants create powerful twisting (torsion) forces These forces can literally tear (shear)

a building apart Reinforcing a frame by attaching or placing a rigid wall inside it

maintains that shape of the frame and prevents rotation at the joints shear walls are

especially important in high-rise building subjected to lateral wind and seismic forces

In the last two decades shear walls became an important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structure are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at those floors

Purpose of constructing shear walls

1 Shear walls are not only designed to resist gravityvertical loads due to its self weight

amp other living moving loads) but they are also designed for lateral loads of

earthquakeswind The walls are structurally integrated with roofsfloors (diaphragms)

and other lateral

2Shear wall structural systems are more stable because their supporting area (Total

cross sectional area of all shear walls) with reference to total plans area of building is

comparatively more unlike in the case of RCC framed structures

3 Walls have to resist the uplift forces caused by the pull of the wind walls have to

resist the shear forces that try to push the walls over walls have to resist the lateral force

of the wind that tries to push the walls in and pull them away from the building

4 Walls floors and roofs to the ground foundation in a direction parallel to their planes

Lateral forces caused by wind earthquake and uneven settlement loads In addition to the

weight of structure and occupants create powerful twisting (torsion) forces These forces

can literally tear (shear) a building apart Reinforcing a frame by attaching or placing a

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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MODULAR HOMES

Modular homes are houses divided into multiple modules sections which are

manufactured in a remote facility and then delivered to their intended site of use The

modules are assembled into a single residential building using either a crane or trucks

Steel andor wood framing are common options for building a modular homes Modular

components are typically constructed within a large indoor facility on assembly lines

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Modular homes

Indoor Construction of modular homes

Such dwellings are often priced lower than their site-built counterparts and are typically

more cost-effective to builders and consumers These new homes can be constructed in

less time than it takes to build a home on-siteldquo

Importance of modular homes

1 Indoor construction Assembly is independent of weather which increases work

efficiency and avoids damaged building material

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2 Favourable pricing from suppliers Large-scale manufacturers can effectively

bargain with suppliers for discounts on materials

3 Ability to service remote locations Particularly in countries such as Australia

there can be much higher costs to build a site-built house in a remote area or an

area experiencing a construction boom such as mining towns Modular homes can

be built in major towns and sold to regional areas

4 Low waste With the same plans being constantly built the manufacturer has

records of exactly what quantity of materials is needed for a given job While

waste from a site-built dwelling may typically fill several large dumpsters waste

from a modular dwelling generates much less waste

5 Building Strength According to manufacturers modular homes are generally

designed to be initially stronger than traditional homesFor example replacing

nails with screws and adding glue to joints This is supposed to help the modules

maintain their structural integrity as they are transported on trucks to the

construction site

6 Assembly Time The modules that will combine to form the house are assembled

off-site in a factory These modules can take one to three months to be constructed

but often take as little as 10 days to actually construct when they are first started

Then they are transported to the building site where a crane is brought in to

assemble the modules togetherThe placement of the modules together generally

takes several hours or days

Mobile Homes

Mobile homes or static caravans are prefabricated homes built in factories rather than on

site and then taken to the place where they will be occupied They are usually

transported by tractor-trailers over public roads to sites which are often in rural areas or

high-density developments In some countries they are used for temporary

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accommodation on campsites While these houses are usually placed in one location and

left there permanently or they have the ability to be move

Behind the work fitted at installation to hide the base there are strong trailer frames

axles wheels and tow-hitches The two major sizes are single-wides and double-wides

1 Single-wides are eighteen feet or less in width and 90 feet (27 m) or less in length

and can be towed to their site as a single unit

Double-wides are twenty feet or more wide and are 90 feet (27 m) in length or less and

are towed to their site in two separate units which are then joined together

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Mobile homes

Production Transportation and Erection

Considerations in production

The general rule is that the connection device must be as lsquofoolproofrsquo as possible It

should be possible to place it in the mould correctly oriented and within the necessary

tolerances with a minimum of effort

1 Avoid congestion

At the location of connections additional reinforcing steel embedded plates

inserts block-outs etc are frequently required It is not unusual that so many items are

concentrated in a small location that very little room is left for the concrete It must be

kept in mind that reinforcing bars and prestressing strands which appear as lines on the

drawing take up real space in the elements Reinforcing bars require more space than

their nominal diameter and there must be room for the curvature of bent bars If

congestion is suspected it is helpful to draw large-scale details of the region in question

2 Avoid penetration of the forms

Units requiring holes in the forms should be avoided if possible especially in steel

moulds Exceptions to this rule can be made if there is a substantial amount of repetition

in the production Holes in the forms may be necessary not only because the units are

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protruding from the elements but also for the arrangement used to keep the units in place

during casting The units must also be designed so that they do not make the dismantling

of the form impossible without damage to the form Most forms are supposed to be used

more than once Connection units to be placed in the top surface during casting should be

secured against the edges of the mould using purpose made holding devices These

devices are mostly costly make it more difficult to obtain a smooth surface or the

holding device may hamper the placement of concrete or other surface material The

various disadvantages have to be evaluated before selecting the method However if the

same steel plate is placed in the bottom of the form it can be located with great accuracy

as it can be fixed to the bottom directly

3 Reduce post-stripping work

A plant casting operation is most efficient when the product can be taken directly

to the storage area immediately after removal from the form Any operations required

after stripping and before erection such as special cleaning or finishing welding on

projecting hardware etc should be avoided These operations require additional handling

(increased possibility of damage to the elements) extra workspace and added labour

often with skilled trades Sometimes a trade-off is necessary between penetration of the

forms and post-stripping work

4 Use repetitious details

It is very desirable to repeat details as much as possible Similar details should be

identical even ifit results in a slight over-design

5 Use standard items

Hardware items such as inserts studs steel elements etc should be readily

available standard items that are preferably from more than one supplier It also

simplifies fabrication if similar product items are standardised as to size and shape There

is also less chance of error The same principle applies to reinforcing bars embedded

plates etc

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6 Be aware of material limitations

Examples of this are the radius requirements for bending reinforcing bars standard

lengths for

certain sizes of inserts etc

7 Avoid non-standard tolerances

Dimensional tolerances which are specified to be more rigid than industry

standards are difficult to achieve Connections which require close-fitting parts without

provision for adjustment should be avoided as much as possible

8 Allow alternatives

Very often precasters will prefer certain details The producer should be allowed

to use alternative methods or materials provided the design requirements are met

Allowing alternative solutions willoften result in the most economical and best

performing connections

Considerations for transportation

During transportation any units protruding from the concrete element must be

shielded in order not to create a hazard to people Protruding units must be able to

withstand any shocks they can be subjected to during handling Protruding units like

reinforcing bars can in many cases be difficult to handle during transportation For

example a wall panel shall be transported standing at the edge but has reinforcing bars

protruding at the bottom This will make it necessary to build up the support on the

trucks which is costly takes time and makes the load less stable This problem can be

solved by letting the bars protrude from the top of the element but then the total height

may make it difficult to negotiate the underpasses en route The solution may then be to

have the protruding bars replaced by insert and threaded bar to screw in after the element

has been transported to the site

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If protruding units do not create the kind of problems described above because

they do not stick out that much there still may be some difficulties For example corbels

pointing down during transport may necessitate a lot of additional support provisions for

the columns on the trucks The consequence can be a less stable load or decreased

loading capacity of the truck This kind of problem can be solved by making columns

with the corbels in one plane only and then place every second column lsquotop-to-bottomrsquo

on the trucks Otherwise it is also possible to look for a corbel-free solution

Considerations for Erection

To fully realise this benefit of fast erection of a precast structure and to keep the

costs within reasonable limits field connections should be kept simple In order to fulfil

the design requirements it is sometimes necessary to compromise fabrication and

erection simplicity

1 Use connections that are not weather sensitive

Materials such as grout dry pack cast-in-place concrete and epoxies need special

provisions to be placed in cold weather Welding is slower when the ambient temperature

is low If the connections are designed so that these processes must be completed before

erection can continue costly delays may result

2 Stability of the elements

Some elements may require propping shoring bracing or fastening before the

hoist can be unhooked Planning for the fewest quickest and safest possible operations to

be executed before releasing the hoist will greatly facilitate the erection

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3 Stability of the structure

In every stage of the erection process the stability of the structure as a whole must

be planned and assured If not costly additional measures may have to be taken The

type of connection used may play a decisive role in this

4 Be aware of possible different loading conditions during erection

During erection loading conditions can occur which induce stresses or

deformations as well in the precast concrete units as in the connections which are higher

than those under service conditions When designing the connections due consideration

has to be paid to these effects unless special measures are taken during the erection such

as temporary supports etc to prevent such situations

5 Standardize connection types

All connections which serve similar functions within the building should be

standardized as much as possible As workmen become familiar with the procedures

required to make the connection productivity is enhanced and there is less chance for

error

Some types of connections require skilled craftsmen to accomplish for example

welding and post tensioning The fewer of these skilled trades required the more

economical the connection will be

6 Standardize sizes of components

Whenever possible such things as field bolts loose angles etc should be of

common size for all connections This reduces the chance for error and the time required

searching for the proper item

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7 Use connections that are not susceptible to damage in handling

Reinforcing bars steel plates dowels and bolts that project from the precast piece

will often be damaged in handling requiring repair to make them fit especially if they

are of small diameter or thickness

Connection detail that makes erection impossible

Support solution that makes erection impossible

SHEAR WALL

Shear walls are vertical elements of the horizontal force resisting system Shear walls are

constructed to counter the effects of lateral load acting on a structure In residential

construction shear walls are straight external walls that typically form a box which

provides all of the lateral support for the building

Importance of shear wall

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When shear walls are designed and constructed property and they will have the strength

and stiffness to resist the horizontal forces In building construction a rigid vertical

diaphragm capable of transferring lateral forces from exterior walls floors and roofs to

the ground foundation in a direction parallel to their planes Lateral forces caused by

wind earthquake and uneven settlement loads In addition to the weight of structure and

occupants create powerful twisting (torsion) forces These forces can literally tear (shear)

a building apart Reinforcing a frame by attaching or placing a rigid wall inside it

maintains that shape of the frame and prevents rotation at the joints shear walls are

especially important in high-rise building subjected to lateral wind and seismic forces

In the last two decades shear walls became an important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structure are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at those floors

Purpose of constructing shear walls

1 Shear walls are not only designed to resist gravityvertical loads due to its self weight

amp other living moving loads) but they are also designed for lateral loads of

earthquakeswind The walls are structurally integrated with roofsfloors (diaphragms)

and other lateral

2Shear wall structural systems are more stable because their supporting area (Total

cross sectional area of all shear walls) with reference to total plans area of building is

comparatively more unlike in the case of RCC framed structures

3 Walls have to resist the uplift forces caused by the pull of the wind walls have to

resist the shear forces that try to push the walls over walls have to resist the lateral force

of the wind that tries to push the walls in and pull them away from the building

4 Walls floors and roofs to the ground foundation in a direction parallel to their planes

Lateral forces caused by wind earthquake and uneven settlement loads In addition to the

weight of structure and occupants create powerful twisting (torsion) forces These forces

can literally tear (shear) a building apart Reinforcing a frame by attaching or placing a

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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Modular homes

Indoor Construction of modular homes

Such dwellings are often priced lower than their site-built counterparts and are typically

more cost-effective to builders and consumers These new homes can be constructed in

less time than it takes to build a home on-siteldquo

Importance of modular homes

1 Indoor construction Assembly is independent of weather which increases work

efficiency and avoids damaged building material

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2 Favourable pricing from suppliers Large-scale manufacturers can effectively

bargain with suppliers for discounts on materials

3 Ability to service remote locations Particularly in countries such as Australia

there can be much higher costs to build a site-built house in a remote area or an

area experiencing a construction boom such as mining towns Modular homes can

be built in major towns and sold to regional areas

4 Low waste With the same plans being constantly built the manufacturer has

records of exactly what quantity of materials is needed for a given job While

waste from a site-built dwelling may typically fill several large dumpsters waste

from a modular dwelling generates much less waste

5 Building Strength According to manufacturers modular homes are generally

designed to be initially stronger than traditional homesFor example replacing

nails with screws and adding glue to joints This is supposed to help the modules

maintain their structural integrity as they are transported on trucks to the

construction site

6 Assembly Time The modules that will combine to form the house are assembled

off-site in a factory These modules can take one to three months to be constructed

but often take as little as 10 days to actually construct when they are first started

Then they are transported to the building site where a crane is brought in to

assemble the modules togetherThe placement of the modules together generally

takes several hours or days

Mobile Homes

Mobile homes or static caravans are prefabricated homes built in factories rather than on

site and then taken to the place where they will be occupied They are usually

transported by tractor-trailers over public roads to sites which are often in rural areas or

high-density developments In some countries they are used for temporary

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accommodation on campsites While these houses are usually placed in one location and

left there permanently or they have the ability to be move

Behind the work fitted at installation to hide the base there are strong trailer frames

axles wheels and tow-hitches The two major sizes are single-wides and double-wides

1 Single-wides are eighteen feet or less in width and 90 feet (27 m) or less in length

and can be towed to their site as a single unit

Double-wides are twenty feet or more wide and are 90 feet (27 m) in length or less and

are towed to their site in two separate units which are then joined together

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Mobile homes

Production Transportation and Erection

Considerations in production

The general rule is that the connection device must be as lsquofoolproofrsquo as possible It

should be possible to place it in the mould correctly oriented and within the necessary

tolerances with a minimum of effort

1 Avoid congestion

At the location of connections additional reinforcing steel embedded plates

inserts block-outs etc are frequently required It is not unusual that so many items are

concentrated in a small location that very little room is left for the concrete It must be

kept in mind that reinforcing bars and prestressing strands which appear as lines on the

drawing take up real space in the elements Reinforcing bars require more space than

their nominal diameter and there must be room for the curvature of bent bars If

congestion is suspected it is helpful to draw large-scale details of the region in question

2 Avoid penetration of the forms

Units requiring holes in the forms should be avoided if possible especially in steel

moulds Exceptions to this rule can be made if there is a substantial amount of repetition

in the production Holes in the forms may be necessary not only because the units are

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protruding from the elements but also for the arrangement used to keep the units in place

during casting The units must also be designed so that they do not make the dismantling

of the form impossible without damage to the form Most forms are supposed to be used

more than once Connection units to be placed in the top surface during casting should be

secured against the edges of the mould using purpose made holding devices These

devices are mostly costly make it more difficult to obtain a smooth surface or the

holding device may hamper the placement of concrete or other surface material The

various disadvantages have to be evaluated before selecting the method However if the

same steel plate is placed in the bottom of the form it can be located with great accuracy

as it can be fixed to the bottom directly

3 Reduce post-stripping work

A plant casting operation is most efficient when the product can be taken directly

to the storage area immediately after removal from the form Any operations required

after stripping and before erection such as special cleaning or finishing welding on

projecting hardware etc should be avoided These operations require additional handling

(increased possibility of damage to the elements) extra workspace and added labour

often with skilled trades Sometimes a trade-off is necessary between penetration of the

forms and post-stripping work

4 Use repetitious details

It is very desirable to repeat details as much as possible Similar details should be

identical even ifit results in a slight over-design

5 Use standard items

Hardware items such as inserts studs steel elements etc should be readily

available standard items that are preferably from more than one supplier It also

simplifies fabrication if similar product items are standardised as to size and shape There

is also less chance of error The same principle applies to reinforcing bars embedded

plates etc

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6 Be aware of material limitations

Examples of this are the radius requirements for bending reinforcing bars standard

lengths for

certain sizes of inserts etc

7 Avoid non-standard tolerances

Dimensional tolerances which are specified to be more rigid than industry

standards are difficult to achieve Connections which require close-fitting parts without

provision for adjustment should be avoided as much as possible

8 Allow alternatives

Very often precasters will prefer certain details The producer should be allowed

to use alternative methods or materials provided the design requirements are met

Allowing alternative solutions willoften result in the most economical and best

performing connections

Considerations for transportation

During transportation any units protruding from the concrete element must be

shielded in order not to create a hazard to people Protruding units must be able to

withstand any shocks they can be subjected to during handling Protruding units like

reinforcing bars can in many cases be difficult to handle during transportation For

example a wall panel shall be transported standing at the edge but has reinforcing bars

protruding at the bottom This will make it necessary to build up the support on the

trucks which is costly takes time and makes the load less stable This problem can be

solved by letting the bars protrude from the top of the element but then the total height

may make it difficult to negotiate the underpasses en route The solution may then be to

have the protruding bars replaced by insert and threaded bar to screw in after the element

has been transported to the site

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If protruding units do not create the kind of problems described above because

they do not stick out that much there still may be some difficulties For example corbels

pointing down during transport may necessitate a lot of additional support provisions for

the columns on the trucks The consequence can be a less stable load or decreased

loading capacity of the truck This kind of problem can be solved by making columns

with the corbels in one plane only and then place every second column lsquotop-to-bottomrsquo

on the trucks Otherwise it is also possible to look for a corbel-free solution

Considerations for Erection

To fully realise this benefit of fast erection of a precast structure and to keep the

costs within reasonable limits field connections should be kept simple In order to fulfil

the design requirements it is sometimes necessary to compromise fabrication and

erection simplicity

1 Use connections that are not weather sensitive

Materials such as grout dry pack cast-in-place concrete and epoxies need special

provisions to be placed in cold weather Welding is slower when the ambient temperature

is low If the connections are designed so that these processes must be completed before

erection can continue costly delays may result

2 Stability of the elements

Some elements may require propping shoring bracing or fastening before the

hoist can be unhooked Planning for the fewest quickest and safest possible operations to

be executed before releasing the hoist will greatly facilitate the erection

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3 Stability of the structure

In every stage of the erection process the stability of the structure as a whole must

be planned and assured If not costly additional measures may have to be taken The

type of connection used may play a decisive role in this

4 Be aware of possible different loading conditions during erection

During erection loading conditions can occur which induce stresses or

deformations as well in the precast concrete units as in the connections which are higher

than those under service conditions When designing the connections due consideration

has to be paid to these effects unless special measures are taken during the erection such

as temporary supports etc to prevent such situations

5 Standardize connection types

All connections which serve similar functions within the building should be

standardized as much as possible As workmen become familiar with the procedures

required to make the connection productivity is enhanced and there is less chance for

error

Some types of connections require skilled craftsmen to accomplish for example

welding and post tensioning The fewer of these skilled trades required the more

economical the connection will be

6 Standardize sizes of components

Whenever possible such things as field bolts loose angles etc should be of

common size for all connections This reduces the chance for error and the time required

searching for the proper item

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7 Use connections that are not susceptible to damage in handling

Reinforcing bars steel plates dowels and bolts that project from the precast piece

will often be damaged in handling requiring repair to make them fit especially if they

are of small diameter or thickness

Connection detail that makes erection impossible

Support solution that makes erection impossible

SHEAR WALL

Shear walls are vertical elements of the horizontal force resisting system Shear walls are

constructed to counter the effects of lateral load acting on a structure In residential

construction shear walls are straight external walls that typically form a box which

provides all of the lateral support for the building

Importance of shear wall

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When shear walls are designed and constructed property and they will have the strength

and stiffness to resist the horizontal forces In building construction a rigid vertical

diaphragm capable of transferring lateral forces from exterior walls floors and roofs to

the ground foundation in a direction parallel to their planes Lateral forces caused by

wind earthquake and uneven settlement loads In addition to the weight of structure and

occupants create powerful twisting (torsion) forces These forces can literally tear (shear)

a building apart Reinforcing a frame by attaching or placing a rigid wall inside it

maintains that shape of the frame and prevents rotation at the joints shear walls are

especially important in high-rise building subjected to lateral wind and seismic forces

In the last two decades shear walls became an important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structure are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at those floors

Purpose of constructing shear walls

1 Shear walls are not only designed to resist gravityvertical loads due to its self weight

amp other living moving loads) but they are also designed for lateral loads of

earthquakeswind The walls are structurally integrated with roofsfloors (diaphragms)

and other lateral

2Shear wall structural systems are more stable because their supporting area (Total

cross sectional area of all shear walls) with reference to total plans area of building is

comparatively more unlike in the case of RCC framed structures

3 Walls have to resist the uplift forces caused by the pull of the wind walls have to

resist the shear forces that try to push the walls over walls have to resist the lateral force

of the wind that tries to push the walls in and pull them away from the building

4 Walls floors and roofs to the ground foundation in a direction parallel to their planes

Lateral forces caused by wind earthquake and uneven settlement loads In addition to the

weight of structure and occupants create powerful twisting (torsion) forces These forces

can literally tear (shear) a building apart Reinforcing a frame by attaching or placing a

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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2 Favourable pricing from suppliers Large-scale manufacturers can effectively

bargain with suppliers for discounts on materials

3 Ability to service remote locations Particularly in countries such as Australia

there can be much higher costs to build a site-built house in a remote area or an

area experiencing a construction boom such as mining towns Modular homes can

be built in major towns and sold to regional areas

4 Low waste With the same plans being constantly built the manufacturer has

records of exactly what quantity of materials is needed for a given job While

waste from a site-built dwelling may typically fill several large dumpsters waste

from a modular dwelling generates much less waste

5 Building Strength According to manufacturers modular homes are generally

designed to be initially stronger than traditional homesFor example replacing

nails with screws and adding glue to joints This is supposed to help the modules

maintain their structural integrity as they are transported on trucks to the

construction site

6 Assembly Time The modules that will combine to form the house are assembled

off-site in a factory These modules can take one to three months to be constructed

but often take as little as 10 days to actually construct when they are first started

Then they are transported to the building site where a crane is brought in to

assemble the modules togetherThe placement of the modules together generally

takes several hours or days

Mobile Homes

Mobile homes or static caravans are prefabricated homes built in factories rather than on

site and then taken to the place where they will be occupied They are usually

transported by tractor-trailers over public roads to sites which are often in rural areas or

high-density developments In some countries they are used for temporary

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accommodation on campsites While these houses are usually placed in one location and

left there permanently or they have the ability to be move

Behind the work fitted at installation to hide the base there are strong trailer frames

axles wheels and tow-hitches The two major sizes are single-wides and double-wides

1 Single-wides are eighteen feet or less in width and 90 feet (27 m) or less in length

and can be towed to their site as a single unit

Double-wides are twenty feet or more wide and are 90 feet (27 m) in length or less and

are towed to their site in two separate units which are then joined together

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Mobile homes

Production Transportation and Erection

Considerations in production

The general rule is that the connection device must be as lsquofoolproofrsquo as possible It

should be possible to place it in the mould correctly oriented and within the necessary

tolerances with a minimum of effort

1 Avoid congestion

At the location of connections additional reinforcing steel embedded plates

inserts block-outs etc are frequently required It is not unusual that so many items are

concentrated in a small location that very little room is left for the concrete It must be

kept in mind that reinforcing bars and prestressing strands which appear as lines on the

drawing take up real space in the elements Reinforcing bars require more space than

their nominal diameter and there must be room for the curvature of bent bars If

congestion is suspected it is helpful to draw large-scale details of the region in question

2 Avoid penetration of the forms

Units requiring holes in the forms should be avoided if possible especially in steel

moulds Exceptions to this rule can be made if there is a substantial amount of repetition

in the production Holes in the forms may be necessary not only because the units are

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protruding from the elements but also for the arrangement used to keep the units in place

during casting The units must also be designed so that they do not make the dismantling

of the form impossible without damage to the form Most forms are supposed to be used

more than once Connection units to be placed in the top surface during casting should be

secured against the edges of the mould using purpose made holding devices These

devices are mostly costly make it more difficult to obtain a smooth surface or the

holding device may hamper the placement of concrete or other surface material The

various disadvantages have to be evaluated before selecting the method However if the

same steel plate is placed in the bottom of the form it can be located with great accuracy

as it can be fixed to the bottom directly

3 Reduce post-stripping work

A plant casting operation is most efficient when the product can be taken directly

to the storage area immediately after removal from the form Any operations required

after stripping and before erection such as special cleaning or finishing welding on

projecting hardware etc should be avoided These operations require additional handling

(increased possibility of damage to the elements) extra workspace and added labour

often with skilled trades Sometimes a trade-off is necessary between penetration of the

forms and post-stripping work

4 Use repetitious details

It is very desirable to repeat details as much as possible Similar details should be

identical even ifit results in a slight over-design

5 Use standard items

Hardware items such as inserts studs steel elements etc should be readily

available standard items that are preferably from more than one supplier It also

simplifies fabrication if similar product items are standardised as to size and shape There

is also less chance of error The same principle applies to reinforcing bars embedded

plates etc

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6 Be aware of material limitations

Examples of this are the radius requirements for bending reinforcing bars standard

lengths for

certain sizes of inserts etc

7 Avoid non-standard tolerances

Dimensional tolerances which are specified to be more rigid than industry

standards are difficult to achieve Connections which require close-fitting parts without

provision for adjustment should be avoided as much as possible

8 Allow alternatives

Very often precasters will prefer certain details The producer should be allowed

to use alternative methods or materials provided the design requirements are met

Allowing alternative solutions willoften result in the most economical and best

performing connections

Considerations for transportation

During transportation any units protruding from the concrete element must be

shielded in order not to create a hazard to people Protruding units must be able to

withstand any shocks they can be subjected to during handling Protruding units like

reinforcing bars can in many cases be difficult to handle during transportation For

example a wall panel shall be transported standing at the edge but has reinforcing bars

protruding at the bottom This will make it necessary to build up the support on the

trucks which is costly takes time and makes the load less stable This problem can be

solved by letting the bars protrude from the top of the element but then the total height

may make it difficult to negotiate the underpasses en route The solution may then be to

have the protruding bars replaced by insert and threaded bar to screw in after the element

has been transported to the site

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If protruding units do not create the kind of problems described above because

they do not stick out that much there still may be some difficulties For example corbels

pointing down during transport may necessitate a lot of additional support provisions for

the columns on the trucks The consequence can be a less stable load or decreased

loading capacity of the truck This kind of problem can be solved by making columns

with the corbels in one plane only and then place every second column lsquotop-to-bottomrsquo

on the trucks Otherwise it is also possible to look for a corbel-free solution

Considerations for Erection

To fully realise this benefit of fast erection of a precast structure and to keep the

costs within reasonable limits field connections should be kept simple In order to fulfil

the design requirements it is sometimes necessary to compromise fabrication and

erection simplicity

1 Use connections that are not weather sensitive

Materials such as grout dry pack cast-in-place concrete and epoxies need special

provisions to be placed in cold weather Welding is slower when the ambient temperature

is low If the connections are designed so that these processes must be completed before

erection can continue costly delays may result

2 Stability of the elements

Some elements may require propping shoring bracing or fastening before the

hoist can be unhooked Planning for the fewest quickest and safest possible operations to

be executed before releasing the hoist will greatly facilitate the erection

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3 Stability of the structure

In every stage of the erection process the stability of the structure as a whole must

be planned and assured If not costly additional measures may have to be taken The

type of connection used may play a decisive role in this

4 Be aware of possible different loading conditions during erection

During erection loading conditions can occur which induce stresses or

deformations as well in the precast concrete units as in the connections which are higher

than those under service conditions When designing the connections due consideration

has to be paid to these effects unless special measures are taken during the erection such

as temporary supports etc to prevent such situations

5 Standardize connection types

All connections which serve similar functions within the building should be

standardized as much as possible As workmen become familiar with the procedures

required to make the connection productivity is enhanced and there is less chance for

error

Some types of connections require skilled craftsmen to accomplish for example

welding and post tensioning The fewer of these skilled trades required the more

economical the connection will be

6 Standardize sizes of components

Whenever possible such things as field bolts loose angles etc should be of

common size for all connections This reduces the chance for error and the time required

searching for the proper item

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7 Use connections that are not susceptible to damage in handling

Reinforcing bars steel plates dowels and bolts that project from the precast piece

will often be damaged in handling requiring repair to make them fit especially if they

are of small diameter or thickness

Connection detail that makes erection impossible

Support solution that makes erection impossible

SHEAR WALL

Shear walls are vertical elements of the horizontal force resisting system Shear walls are

constructed to counter the effects of lateral load acting on a structure In residential

construction shear walls are straight external walls that typically form a box which

provides all of the lateral support for the building

Importance of shear wall

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When shear walls are designed and constructed property and they will have the strength

and stiffness to resist the horizontal forces In building construction a rigid vertical

diaphragm capable of transferring lateral forces from exterior walls floors and roofs to

the ground foundation in a direction parallel to their planes Lateral forces caused by

wind earthquake and uneven settlement loads In addition to the weight of structure and

occupants create powerful twisting (torsion) forces These forces can literally tear (shear)

a building apart Reinforcing a frame by attaching or placing a rigid wall inside it

maintains that shape of the frame and prevents rotation at the joints shear walls are

especially important in high-rise building subjected to lateral wind and seismic forces

In the last two decades shear walls became an important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structure are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at those floors

Purpose of constructing shear walls

1 Shear walls are not only designed to resist gravityvertical loads due to its self weight

amp other living moving loads) but they are also designed for lateral loads of

earthquakeswind The walls are structurally integrated with roofsfloors (diaphragms)

and other lateral

2Shear wall structural systems are more stable because their supporting area (Total

cross sectional area of all shear walls) with reference to total plans area of building is

comparatively more unlike in the case of RCC framed structures

3 Walls have to resist the uplift forces caused by the pull of the wind walls have to

resist the shear forces that try to push the walls over walls have to resist the lateral force

of the wind that tries to push the walls in and pull them away from the building

4 Walls floors and roofs to the ground foundation in a direction parallel to their planes

Lateral forces caused by wind earthquake and uneven settlement loads In addition to the

weight of structure and occupants create powerful twisting (torsion) forces These forces

can literally tear (shear) a building apart Reinforcing a frame by attaching or placing a

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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accommodation on campsites While these houses are usually placed in one location and

left there permanently or they have the ability to be move

Behind the work fitted at installation to hide the base there are strong trailer frames

axles wheels and tow-hitches The two major sizes are single-wides and double-wides

1 Single-wides are eighteen feet or less in width and 90 feet (27 m) or less in length

and can be towed to their site as a single unit

Double-wides are twenty feet or more wide and are 90 feet (27 m) in length or less and

are towed to their site in two separate units which are then joined together

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Mobile homes

Production Transportation and Erection

Considerations in production

The general rule is that the connection device must be as lsquofoolproofrsquo as possible It

should be possible to place it in the mould correctly oriented and within the necessary

tolerances with a minimum of effort

1 Avoid congestion

At the location of connections additional reinforcing steel embedded plates

inserts block-outs etc are frequently required It is not unusual that so many items are

concentrated in a small location that very little room is left for the concrete It must be

kept in mind that reinforcing bars and prestressing strands which appear as lines on the

drawing take up real space in the elements Reinforcing bars require more space than

their nominal diameter and there must be room for the curvature of bent bars If

congestion is suspected it is helpful to draw large-scale details of the region in question

2 Avoid penetration of the forms

Units requiring holes in the forms should be avoided if possible especially in steel

moulds Exceptions to this rule can be made if there is a substantial amount of repetition

in the production Holes in the forms may be necessary not only because the units are

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protruding from the elements but also for the arrangement used to keep the units in place

during casting The units must also be designed so that they do not make the dismantling

of the form impossible without damage to the form Most forms are supposed to be used

more than once Connection units to be placed in the top surface during casting should be

secured against the edges of the mould using purpose made holding devices These

devices are mostly costly make it more difficult to obtain a smooth surface or the

holding device may hamper the placement of concrete or other surface material The

various disadvantages have to be evaluated before selecting the method However if the

same steel plate is placed in the bottom of the form it can be located with great accuracy

as it can be fixed to the bottom directly

3 Reduce post-stripping work

A plant casting operation is most efficient when the product can be taken directly

to the storage area immediately after removal from the form Any operations required

after stripping and before erection such as special cleaning or finishing welding on

projecting hardware etc should be avoided These operations require additional handling

(increased possibility of damage to the elements) extra workspace and added labour

often with skilled trades Sometimes a trade-off is necessary between penetration of the

forms and post-stripping work

4 Use repetitious details

It is very desirable to repeat details as much as possible Similar details should be

identical even ifit results in a slight over-design

5 Use standard items

Hardware items such as inserts studs steel elements etc should be readily

available standard items that are preferably from more than one supplier It also

simplifies fabrication if similar product items are standardised as to size and shape There

is also less chance of error The same principle applies to reinforcing bars embedded

plates etc

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6 Be aware of material limitations

Examples of this are the radius requirements for bending reinforcing bars standard

lengths for

certain sizes of inserts etc

7 Avoid non-standard tolerances

Dimensional tolerances which are specified to be more rigid than industry

standards are difficult to achieve Connections which require close-fitting parts without

provision for adjustment should be avoided as much as possible

8 Allow alternatives

Very often precasters will prefer certain details The producer should be allowed

to use alternative methods or materials provided the design requirements are met

Allowing alternative solutions willoften result in the most economical and best

performing connections

Considerations for transportation

During transportation any units protruding from the concrete element must be

shielded in order not to create a hazard to people Protruding units must be able to

withstand any shocks they can be subjected to during handling Protruding units like

reinforcing bars can in many cases be difficult to handle during transportation For

example a wall panel shall be transported standing at the edge but has reinforcing bars

protruding at the bottom This will make it necessary to build up the support on the

trucks which is costly takes time and makes the load less stable This problem can be

solved by letting the bars protrude from the top of the element but then the total height

may make it difficult to negotiate the underpasses en route The solution may then be to

have the protruding bars replaced by insert and threaded bar to screw in after the element

has been transported to the site

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If protruding units do not create the kind of problems described above because

they do not stick out that much there still may be some difficulties For example corbels

pointing down during transport may necessitate a lot of additional support provisions for

the columns on the trucks The consequence can be a less stable load or decreased

loading capacity of the truck This kind of problem can be solved by making columns

with the corbels in one plane only and then place every second column lsquotop-to-bottomrsquo

on the trucks Otherwise it is also possible to look for a corbel-free solution

Considerations for Erection

To fully realise this benefit of fast erection of a precast structure and to keep the

costs within reasonable limits field connections should be kept simple In order to fulfil

the design requirements it is sometimes necessary to compromise fabrication and

erection simplicity

1 Use connections that are not weather sensitive

Materials such as grout dry pack cast-in-place concrete and epoxies need special

provisions to be placed in cold weather Welding is slower when the ambient temperature

is low If the connections are designed so that these processes must be completed before

erection can continue costly delays may result

2 Stability of the elements

Some elements may require propping shoring bracing or fastening before the

hoist can be unhooked Planning for the fewest quickest and safest possible operations to

be executed before releasing the hoist will greatly facilitate the erection

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3 Stability of the structure

In every stage of the erection process the stability of the structure as a whole must

be planned and assured If not costly additional measures may have to be taken The

type of connection used may play a decisive role in this

4 Be aware of possible different loading conditions during erection

During erection loading conditions can occur which induce stresses or

deformations as well in the precast concrete units as in the connections which are higher

than those under service conditions When designing the connections due consideration

has to be paid to these effects unless special measures are taken during the erection such

as temporary supports etc to prevent such situations

5 Standardize connection types

All connections which serve similar functions within the building should be

standardized as much as possible As workmen become familiar with the procedures

required to make the connection productivity is enhanced and there is less chance for

error

Some types of connections require skilled craftsmen to accomplish for example

welding and post tensioning The fewer of these skilled trades required the more

economical the connection will be

6 Standardize sizes of components

Whenever possible such things as field bolts loose angles etc should be of

common size for all connections This reduces the chance for error and the time required

searching for the proper item

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7 Use connections that are not susceptible to damage in handling

Reinforcing bars steel plates dowels and bolts that project from the precast piece

will often be damaged in handling requiring repair to make them fit especially if they

are of small diameter or thickness

Connection detail that makes erection impossible

Support solution that makes erection impossible

SHEAR WALL

Shear walls are vertical elements of the horizontal force resisting system Shear walls are

constructed to counter the effects of lateral load acting on a structure In residential

construction shear walls are straight external walls that typically form a box which

provides all of the lateral support for the building

Importance of shear wall

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When shear walls are designed and constructed property and they will have the strength

and stiffness to resist the horizontal forces In building construction a rigid vertical

diaphragm capable of transferring lateral forces from exterior walls floors and roofs to

the ground foundation in a direction parallel to their planes Lateral forces caused by

wind earthquake and uneven settlement loads In addition to the weight of structure and

occupants create powerful twisting (torsion) forces These forces can literally tear (shear)

a building apart Reinforcing a frame by attaching or placing a rigid wall inside it

maintains that shape of the frame and prevents rotation at the joints shear walls are

especially important in high-rise building subjected to lateral wind and seismic forces

In the last two decades shear walls became an important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structure are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at those floors

Purpose of constructing shear walls

1 Shear walls are not only designed to resist gravityvertical loads due to its self weight

amp other living moving loads) but they are also designed for lateral loads of

earthquakeswind The walls are structurally integrated with roofsfloors (diaphragms)

and other lateral

2Shear wall structural systems are more stable because their supporting area (Total

cross sectional area of all shear walls) with reference to total plans area of building is

comparatively more unlike in the case of RCC framed structures

3 Walls have to resist the uplift forces caused by the pull of the wind walls have to

resist the shear forces that try to push the walls over walls have to resist the lateral force

of the wind that tries to push the walls in and pull them away from the building

4 Walls floors and roofs to the ground foundation in a direction parallel to their planes

Lateral forces caused by wind earthquake and uneven settlement loads In addition to the

weight of structure and occupants create powerful twisting (torsion) forces These forces

can literally tear (shear) a building apart Reinforcing a frame by attaching or placing a

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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Mobile homes

Production Transportation and Erection

Considerations in production

The general rule is that the connection device must be as lsquofoolproofrsquo as possible It

should be possible to place it in the mould correctly oriented and within the necessary

tolerances with a minimum of effort

1 Avoid congestion

At the location of connections additional reinforcing steel embedded plates

inserts block-outs etc are frequently required It is not unusual that so many items are

concentrated in a small location that very little room is left for the concrete It must be

kept in mind that reinforcing bars and prestressing strands which appear as lines on the

drawing take up real space in the elements Reinforcing bars require more space than

their nominal diameter and there must be room for the curvature of bent bars If

congestion is suspected it is helpful to draw large-scale details of the region in question

2 Avoid penetration of the forms

Units requiring holes in the forms should be avoided if possible especially in steel

moulds Exceptions to this rule can be made if there is a substantial amount of repetition

in the production Holes in the forms may be necessary not only because the units are

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protruding from the elements but also for the arrangement used to keep the units in place

during casting The units must also be designed so that they do not make the dismantling

of the form impossible without damage to the form Most forms are supposed to be used

more than once Connection units to be placed in the top surface during casting should be

secured against the edges of the mould using purpose made holding devices These

devices are mostly costly make it more difficult to obtain a smooth surface or the

holding device may hamper the placement of concrete or other surface material The

various disadvantages have to be evaluated before selecting the method However if the

same steel plate is placed in the bottom of the form it can be located with great accuracy

as it can be fixed to the bottom directly

3 Reduce post-stripping work

A plant casting operation is most efficient when the product can be taken directly

to the storage area immediately after removal from the form Any operations required

after stripping and before erection such as special cleaning or finishing welding on

projecting hardware etc should be avoided These operations require additional handling

(increased possibility of damage to the elements) extra workspace and added labour

often with skilled trades Sometimes a trade-off is necessary between penetration of the

forms and post-stripping work

4 Use repetitious details

It is very desirable to repeat details as much as possible Similar details should be

identical even ifit results in a slight over-design

5 Use standard items

Hardware items such as inserts studs steel elements etc should be readily

available standard items that are preferably from more than one supplier It also

simplifies fabrication if similar product items are standardised as to size and shape There

is also less chance of error The same principle applies to reinforcing bars embedded

plates etc

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6 Be aware of material limitations

Examples of this are the radius requirements for bending reinforcing bars standard

lengths for

certain sizes of inserts etc

7 Avoid non-standard tolerances

Dimensional tolerances which are specified to be more rigid than industry

standards are difficult to achieve Connections which require close-fitting parts without

provision for adjustment should be avoided as much as possible

8 Allow alternatives

Very often precasters will prefer certain details The producer should be allowed

to use alternative methods or materials provided the design requirements are met

Allowing alternative solutions willoften result in the most economical and best

performing connections

Considerations for transportation

During transportation any units protruding from the concrete element must be

shielded in order not to create a hazard to people Protruding units must be able to

withstand any shocks they can be subjected to during handling Protruding units like

reinforcing bars can in many cases be difficult to handle during transportation For

example a wall panel shall be transported standing at the edge but has reinforcing bars

protruding at the bottom This will make it necessary to build up the support on the

trucks which is costly takes time and makes the load less stable This problem can be

solved by letting the bars protrude from the top of the element but then the total height

may make it difficult to negotiate the underpasses en route The solution may then be to

have the protruding bars replaced by insert and threaded bar to screw in after the element

has been transported to the site

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If protruding units do not create the kind of problems described above because

they do not stick out that much there still may be some difficulties For example corbels

pointing down during transport may necessitate a lot of additional support provisions for

the columns on the trucks The consequence can be a less stable load or decreased

loading capacity of the truck This kind of problem can be solved by making columns

with the corbels in one plane only and then place every second column lsquotop-to-bottomrsquo

on the trucks Otherwise it is also possible to look for a corbel-free solution

Considerations for Erection

To fully realise this benefit of fast erection of a precast structure and to keep the

costs within reasonable limits field connections should be kept simple In order to fulfil

the design requirements it is sometimes necessary to compromise fabrication and

erection simplicity

1 Use connections that are not weather sensitive

Materials such as grout dry pack cast-in-place concrete and epoxies need special

provisions to be placed in cold weather Welding is slower when the ambient temperature

is low If the connections are designed so that these processes must be completed before

erection can continue costly delays may result

2 Stability of the elements

Some elements may require propping shoring bracing or fastening before the

hoist can be unhooked Planning for the fewest quickest and safest possible operations to

be executed before releasing the hoist will greatly facilitate the erection

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3 Stability of the structure

In every stage of the erection process the stability of the structure as a whole must

be planned and assured If not costly additional measures may have to be taken The

type of connection used may play a decisive role in this

4 Be aware of possible different loading conditions during erection

During erection loading conditions can occur which induce stresses or

deformations as well in the precast concrete units as in the connections which are higher

than those under service conditions When designing the connections due consideration

has to be paid to these effects unless special measures are taken during the erection such

as temporary supports etc to prevent such situations

5 Standardize connection types

All connections which serve similar functions within the building should be

standardized as much as possible As workmen become familiar with the procedures

required to make the connection productivity is enhanced and there is less chance for

error

Some types of connections require skilled craftsmen to accomplish for example

welding and post tensioning The fewer of these skilled trades required the more

economical the connection will be

6 Standardize sizes of components

Whenever possible such things as field bolts loose angles etc should be of

common size for all connections This reduces the chance for error and the time required

searching for the proper item

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7 Use connections that are not susceptible to damage in handling

Reinforcing bars steel plates dowels and bolts that project from the precast piece

will often be damaged in handling requiring repair to make them fit especially if they

are of small diameter or thickness

Connection detail that makes erection impossible

Support solution that makes erection impossible

SHEAR WALL

Shear walls are vertical elements of the horizontal force resisting system Shear walls are

constructed to counter the effects of lateral load acting on a structure In residential

construction shear walls are straight external walls that typically form a box which

provides all of the lateral support for the building

Importance of shear wall

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When shear walls are designed and constructed property and they will have the strength

and stiffness to resist the horizontal forces In building construction a rigid vertical

diaphragm capable of transferring lateral forces from exterior walls floors and roofs to

the ground foundation in a direction parallel to their planes Lateral forces caused by

wind earthquake and uneven settlement loads In addition to the weight of structure and

occupants create powerful twisting (torsion) forces These forces can literally tear (shear)

a building apart Reinforcing a frame by attaching or placing a rigid wall inside it

maintains that shape of the frame and prevents rotation at the joints shear walls are

especially important in high-rise building subjected to lateral wind and seismic forces

In the last two decades shear walls became an important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structure are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at those floors

Purpose of constructing shear walls

1 Shear walls are not only designed to resist gravityvertical loads due to its self weight

amp other living moving loads) but they are also designed for lateral loads of

earthquakeswind The walls are structurally integrated with roofsfloors (diaphragms)

and other lateral

2Shear wall structural systems are more stable because their supporting area (Total

cross sectional area of all shear walls) with reference to total plans area of building is

comparatively more unlike in the case of RCC framed structures

3 Walls have to resist the uplift forces caused by the pull of the wind walls have to

resist the shear forces that try to push the walls over walls have to resist the lateral force

of the wind that tries to push the walls in and pull them away from the building

4 Walls floors and roofs to the ground foundation in a direction parallel to their planes

Lateral forces caused by wind earthquake and uneven settlement loads In addition to the

weight of structure and occupants create powerful twisting (torsion) forces These forces

can literally tear (shear) a building apart Reinforcing a frame by attaching or placing a

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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protruding from the elements but also for the arrangement used to keep the units in place

during casting The units must also be designed so that they do not make the dismantling

of the form impossible without damage to the form Most forms are supposed to be used

more than once Connection units to be placed in the top surface during casting should be

secured against the edges of the mould using purpose made holding devices These

devices are mostly costly make it more difficult to obtain a smooth surface or the

holding device may hamper the placement of concrete or other surface material The

various disadvantages have to be evaluated before selecting the method However if the

same steel plate is placed in the bottom of the form it can be located with great accuracy

as it can be fixed to the bottom directly

3 Reduce post-stripping work

A plant casting operation is most efficient when the product can be taken directly

to the storage area immediately after removal from the form Any operations required

after stripping and before erection such as special cleaning or finishing welding on

projecting hardware etc should be avoided These operations require additional handling

(increased possibility of damage to the elements) extra workspace and added labour

often with skilled trades Sometimes a trade-off is necessary between penetration of the

forms and post-stripping work

4 Use repetitious details

It is very desirable to repeat details as much as possible Similar details should be

identical even ifit results in a slight over-design

5 Use standard items

Hardware items such as inserts studs steel elements etc should be readily

available standard items that are preferably from more than one supplier It also

simplifies fabrication if similar product items are standardised as to size and shape There

is also less chance of error The same principle applies to reinforcing bars embedded

plates etc

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6 Be aware of material limitations

Examples of this are the radius requirements for bending reinforcing bars standard

lengths for

certain sizes of inserts etc

7 Avoid non-standard tolerances

Dimensional tolerances which are specified to be more rigid than industry

standards are difficult to achieve Connections which require close-fitting parts without

provision for adjustment should be avoided as much as possible

8 Allow alternatives

Very often precasters will prefer certain details The producer should be allowed

to use alternative methods or materials provided the design requirements are met

Allowing alternative solutions willoften result in the most economical and best

performing connections

Considerations for transportation

During transportation any units protruding from the concrete element must be

shielded in order not to create a hazard to people Protruding units must be able to

withstand any shocks they can be subjected to during handling Protruding units like

reinforcing bars can in many cases be difficult to handle during transportation For

example a wall panel shall be transported standing at the edge but has reinforcing bars

protruding at the bottom This will make it necessary to build up the support on the

trucks which is costly takes time and makes the load less stable This problem can be

solved by letting the bars protrude from the top of the element but then the total height

may make it difficult to negotiate the underpasses en route The solution may then be to

have the protruding bars replaced by insert and threaded bar to screw in after the element

has been transported to the site

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If protruding units do not create the kind of problems described above because

they do not stick out that much there still may be some difficulties For example corbels

pointing down during transport may necessitate a lot of additional support provisions for

the columns on the trucks The consequence can be a less stable load or decreased

loading capacity of the truck This kind of problem can be solved by making columns

with the corbels in one plane only and then place every second column lsquotop-to-bottomrsquo

on the trucks Otherwise it is also possible to look for a corbel-free solution

Considerations for Erection

To fully realise this benefit of fast erection of a precast structure and to keep the

costs within reasonable limits field connections should be kept simple In order to fulfil

the design requirements it is sometimes necessary to compromise fabrication and

erection simplicity

1 Use connections that are not weather sensitive

Materials such as grout dry pack cast-in-place concrete and epoxies need special

provisions to be placed in cold weather Welding is slower when the ambient temperature

is low If the connections are designed so that these processes must be completed before

erection can continue costly delays may result

2 Stability of the elements

Some elements may require propping shoring bracing or fastening before the

hoist can be unhooked Planning for the fewest quickest and safest possible operations to

be executed before releasing the hoist will greatly facilitate the erection

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3 Stability of the structure

In every stage of the erection process the stability of the structure as a whole must

be planned and assured If not costly additional measures may have to be taken The

type of connection used may play a decisive role in this

4 Be aware of possible different loading conditions during erection

During erection loading conditions can occur which induce stresses or

deformations as well in the precast concrete units as in the connections which are higher

than those under service conditions When designing the connections due consideration

has to be paid to these effects unless special measures are taken during the erection such

as temporary supports etc to prevent such situations

5 Standardize connection types

All connections which serve similar functions within the building should be

standardized as much as possible As workmen become familiar with the procedures

required to make the connection productivity is enhanced and there is less chance for

error

Some types of connections require skilled craftsmen to accomplish for example

welding and post tensioning The fewer of these skilled trades required the more

economical the connection will be

6 Standardize sizes of components

Whenever possible such things as field bolts loose angles etc should be of

common size for all connections This reduces the chance for error and the time required

searching for the proper item

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7 Use connections that are not susceptible to damage in handling

Reinforcing bars steel plates dowels and bolts that project from the precast piece

will often be damaged in handling requiring repair to make them fit especially if they

are of small diameter or thickness

Connection detail that makes erection impossible

Support solution that makes erection impossible

SHEAR WALL

Shear walls are vertical elements of the horizontal force resisting system Shear walls are

constructed to counter the effects of lateral load acting on a structure In residential

construction shear walls are straight external walls that typically form a box which

provides all of the lateral support for the building

Importance of shear wall

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When shear walls are designed and constructed property and they will have the strength

and stiffness to resist the horizontal forces In building construction a rigid vertical

diaphragm capable of transferring lateral forces from exterior walls floors and roofs to

the ground foundation in a direction parallel to their planes Lateral forces caused by

wind earthquake and uneven settlement loads In addition to the weight of structure and

occupants create powerful twisting (torsion) forces These forces can literally tear (shear)

a building apart Reinforcing a frame by attaching or placing a rigid wall inside it

maintains that shape of the frame and prevents rotation at the joints shear walls are

especially important in high-rise building subjected to lateral wind and seismic forces

In the last two decades shear walls became an important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structure are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at those floors

Purpose of constructing shear walls

1 Shear walls are not only designed to resist gravityvertical loads due to its self weight

amp other living moving loads) but they are also designed for lateral loads of

earthquakeswind The walls are structurally integrated with roofsfloors (diaphragms)

and other lateral

2Shear wall structural systems are more stable because their supporting area (Total

cross sectional area of all shear walls) with reference to total plans area of building is

comparatively more unlike in the case of RCC framed structures

3 Walls have to resist the uplift forces caused by the pull of the wind walls have to

resist the shear forces that try to push the walls over walls have to resist the lateral force

of the wind that tries to push the walls in and pull them away from the building

4 Walls floors and roofs to the ground foundation in a direction parallel to their planes

Lateral forces caused by wind earthquake and uneven settlement loads In addition to the

weight of structure and occupants create powerful twisting (torsion) forces These forces

can literally tear (shear) a building apart Reinforcing a frame by attaching or placing a

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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6 Be aware of material limitations

Examples of this are the radius requirements for bending reinforcing bars standard

lengths for

certain sizes of inserts etc

7 Avoid non-standard tolerances

Dimensional tolerances which are specified to be more rigid than industry

standards are difficult to achieve Connections which require close-fitting parts without

provision for adjustment should be avoided as much as possible

8 Allow alternatives

Very often precasters will prefer certain details The producer should be allowed

to use alternative methods or materials provided the design requirements are met

Allowing alternative solutions willoften result in the most economical and best

performing connections

Considerations for transportation

During transportation any units protruding from the concrete element must be

shielded in order not to create a hazard to people Protruding units must be able to

withstand any shocks they can be subjected to during handling Protruding units like

reinforcing bars can in many cases be difficult to handle during transportation For

example a wall panel shall be transported standing at the edge but has reinforcing bars

protruding at the bottom This will make it necessary to build up the support on the

trucks which is costly takes time and makes the load less stable This problem can be

solved by letting the bars protrude from the top of the element but then the total height

may make it difficult to negotiate the underpasses en route The solution may then be to

have the protruding bars replaced by insert and threaded bar to screw in after the element

has been transported to the site

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If protruding units do not create the kind of problems described above because

they do not stick out that much there still may be some difficulties For example corbels

pointing down during transport may necessitate a lot of additional support provisions for

the columns on the trucks The consequence can be a less stable load or decreased

loading capacity of the truck This kind of problem can be solved by making columns

with the corbels in one plane only and then place every second column lsquotop-to-bottomrsquo

on the trucks Otherwise it is also possible to look for a corbel-free solution

Considerations for Erection

To fully realise this benefit of fast erection of a precast structure and to keep the

costs within reasonable limits field connections should be kept simple In order to fulfil

the design requirements it is sometimes necessary to compromise fabrication and

erection simplicity

1 Use connections that are not weather sensitive

Materials such as grout dry pack cast-in-place concrete and epoxies need special

provisions to be placed in cold weather Welding is slower when the ambient temperature

is low If the connections are designed so that these processes must be completed before

erection can continue costly delays may result

2 Stability of the elements

Some elements may require propping shoring bracing or fastening before the

hoist can be unhooked Planning for the fewest quickest and safest possible operations to

be executed before releasing the hoist will greatly facilitate the erection

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3 Stability of the structure

In every stage of the erection process the stability of the structure as a whole must

be planned and assured If not costly additional measures may have to be taken The

type of connection used may play a decisive role in this

4 Be aware of possible different loading conditions during erection

During erection loading conditions can occur which induce stresses or

deformations as well in the precast concrete units as in the connections which are higher

than those under service conditions When designing the connections due consideration

has to be paid to these effects unless special measures are taken during the erection such

as temporary supports etc to prevent such situations

5 Standardize connection types

All connections which serve similar functions within the building should be

standardized as much as possible As workmen become familiar with the procedures

required to make the connection productivity is enhanced and there is less chance for

error

Some types of connections require skilled craftsmen to accomplish for example

welding and post tensioning The fewer of these skilled trades required the more

economical the connection will be

6 Standardize sizes of components

Whenever possible such things as field bolts loose angles etc should be of

common size for all connections This reduces the chance for error and the time required

searching for the proper item

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7 Use connections that are not susceptible to damage in handling

Reinforcing bars steel plates dowels and bolts that project from the precast piece

will often be damaged in handling requiring repair to make them fit especially if they

are of small diameter or thickness

Connection detail that makes erection impossible

Support solution that makes erection impossible

SHEAR WALL

Shear walls are vertical elements of the horizontal force resisting system Shear walls are

constructed to counter the effects of lateral load acting on a structure In residential

construction shear walls are straight external walls that typically form a box which

provides all of the lateral support for the building

Importance of shear wall

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When shear walls are designed and constructed property and they will have the strength

and stiffness to resist the horizontal forces In building construction a rigid vertical

diaphragm capable of transferring lateral forces from exterior walls floors and roofs to

the ground foundation in a direction parallel to their planes Lateral forces caused by

wind earthquake and uneven settlement loads In addition to the weight of structure and

occupants create powerful twisting (torsion) forces These forces can literally tear (shear)

a building apart Reinforcing a frame by attaching or placing a rigid wall inside it

maintains that shape of the frame and prevents rotation at the joints shear walls are

especially important in high-rise building subjected to lateral wind and seismic forces

In the last two decades shear walls became an important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structure are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at those floors

Purpose of constructing shear walls

1 Shear walls are not only designed to resist gravityvertical loads due to its self weight

amp other living moving loads) but they are also designed for lateral loads of

earthquakeswind The walls are structurally integrated with roofsfloors (diaphragms)

and other lateral

2Shear wall structural systems are more stable because their supporting area (Total

cross sectional area of all shear walls) with reference to total plans area of building is

comparatively more unlike in the case of RCC framed structures

3 Walls have to resist the uplift forces caused by the pull of the wind walls have to

resist the shear forces that try to push the walls over walls have to resist the lateral force

of the wind that tries to push the walls in and pull them away from the building

4 Walls floors and roofs to the ground foundation in a direction parallel to their planes

Lateral forces caused by wind earthquake and uneven settlement loads In addition to the

weight of structure and occupants create powerful twisting (torsion) forces These forces

can literally tear (shear) a building apart Reinforcing a frame by attaching or placing a

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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If protruding units do not create the kind of problems described above because

they do not stick out that much there still may be some difficulties For example corbels

pointing down during transport may necessitate a lot of additional support provisions for

the columns on the trucks The consequence can be a less stable load or decreased

loading capacity of the truck This kind of problem can be solved by making columns

with the corbels in one plane only and then place every second column lsquotop-to-bottomrsquo

on the trucks Otherwise it is also possible to look for a corbel-free solution

Considerations for Erection

To fully realise this benefit of fast erection of a precast structure and to keep the

costs within reasonable limits field connections should be kept simple In order to fulfil

the design requirements it is sometimes necessary to compromise fabrication and

erection simplicity

1 Use connections that are not weather sensitive

Materials such as grout dry pack cast-in-place concrete and epoxies need special

provisions to be placed in cold weather Welding is slower when the ambient temperature

is low If the connections are designed so that these processes must be completed before

erection can continue costly delays may result

2 Stability of the elements

Some elements may require propping shoring bracing or fastening before the

hoist can be unhooked Planning for the fewest quickest and safest possible operations to

be executed before releasing the hoist will greatly facilitate the erection

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3 Stability of the structure

In every stage of the erection process the stability of the structure as a whole must

be planned and assured If not costly additional measures may have to be taken The

type of connection used may play a decisive role in this

4 Be aware of possible different loading conditions during erection

During erection loading conditions can occur which induce stresses or

deformations as well in the precast concrete units as in the connections which are higher

than those under service conditions When designing the connections due consideration

has to be paid to these effects unless special measures are taken during the erection such

as temporary supports etc to prevent such situations

5 Standardize connection types

All connections which serve similar functions within the building should be

standardized as much as possible As workmen become familiar with the procedures

required to make the connection productivity is enhanced and there is less chance for

error

Some types of connections require skilled craftsmen to accomplish for example

welding and post tensioning The fewer of these skilled trades required the more

economical the connection will be

6 Standardize sizes of components

Whenever possible such things as field bolts loose angles etc should be of

common size for all connections This reduces the chance for error and the time required

searching for the proper item

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7 Use connections that are not susceptible to damage in handling

Reinforcing bars steel plates dowels and bolts that project from the precast piece

will often be damaged in handling requiring repair to make them fit especially if they

are of small diameter or thickness

Connection detail that makes erection impossible

Support solution that makes erection impossible

SHEAR WALL

Shear walls are vertical elements of the horizontal force resisting system Shear walls are

constructed to counter the effects of lateral load acting on a structure In residential

construction shear walls are straight external walls that typically form a box which

provides all of the lateral support for the building

Importance of shear wall

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When shear walls are designed and constructed property and they will have the strength

and stiffness to resist the horizontal forces In building construction a rigid vertical

diaphragm capable of transferring lateral forces from exterior walls floors and roofs to

the ground foundation in a direction parallel to their planes Lateral forces caused by

wind earthquake and uneven settlement loads In addition to the weight of structure and

occupants create powerful twisting (torsion) forces These forces can literally tear (shear)

a building apart Reinforcing a frame by attaching or placing a rigid wall inside it

maintains that shape of the frame and prevents rotation at the joints shear walls are

especially important in high-rise building subjected to lateral wind and seismic forces

In the last two decades shear walls became an important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structure are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at those floors

Purpose of constructing shear walls

1 Shear walls are not only designed to resist gravityvertical loads due to its self weight

amp other living moving loads) but they are also designed for lateral loads of

earthquakeswind The walls are structurally integrated with roofsfloors (diaphragms)

and other lateral

2Shear wall structural systems are more stable because their supporting area (Total

cross sectional area of all shear walls) with reference to total plans area of building is

comparatively more unlike in the case of RCC framed structures

3 Walls have to resist the uplift forces caused by the pull of the wind walls have to

resist the shear forces that try to push the walls over walls have to resist the lateral force

of the wind that tries to push the walls in and pull them away from the building

4 Walls floors and roofs to the ground foundation in a direction parallel to their planes

Lateral forces caused by wind earthquake and uneven settlement loads In addition to the

weight of structure and occupants create powerful twisting (torsion) forces These forces

can literally tear (shear) a building apart Reinforcing a frame by attaching or placing a

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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3 Stability of the structure

In every stage of the erection process the stability of the structure as a whole must

be planned and assured If not costly additional measures may have to be taken The

type of connection used may play a decisive role in this

4 Be aware of possible different loading conditions during erection

During erection loading conditions can occur which induce stresses or

deformations as well in the precast concrete units as in the connections which are higher

than those under service conditions When designing the connections due consideration

has to be paid to these effects unless special measures are taken during the erection such

as temporary supports etc to prevent such situations

5 Standardize connection types

All connections which serve similar functions within the building should be

standardized as much as possible As workmen become familiar with the procedures

required to make the connection productivity is enhanced and there is less chance for

error

Some types of connections require skilled craftsmen to accomplish for example

welding and post tensioning The fewer of these skilled trades required the more

economical the connection will be

6 Standardize sizes of components

Whenever possible such things as field bolts loose angles etc should be of

common size for all connections This reduces the chance for error and the time required

searching for the proper item

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7 Use connections that are not susceptible to damage in handling

Reinforcing bars steel plates dowels and bolts that project from the precast piece

will often be damaged in handling requiring repair to make them fit especially if they

are of small diameter or thickness

Connection detail that makes erection impossible

Support solution that makes erection impossible

SHEAR WALL

Shear walls are vertical elements of the horizontal force resisting system Shear walls are

constructed to counter the effects of lateral load acting on a structure In residential

construction shear walls are straight external walls that typically form a box which

provides all of the lateral support for the building

Importance of shear wall

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When shear walls are designed and constructed property and they will have the strength

and stiffness to resist the horizontal forces In building construction a rigid vertical

diaphragm capable of transferring lateral forces from exterior walls floors and roofs to

the ground foundation in a direction parallel to their planes Lateral forces caused by

wind earthquake and uneven settlement loads In addition to the weight of structure and

occupants create powerful twisting (torsion) forces These forces can literally tear (shear)

a building apart Reinforcing a frame by attaching or placing a rigid wall inside it

maintains that shape of the frame and prevents rotation at the joints shear walls are

especially important in high-rise building subjected to lateral wind and seismic forces

In the last two decades shear walls became an important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structure are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at those floors

Purpose of constructing shear walls

1 Shear walls are not only designed to resist gravityvertical loads due to its self weight

amp other living moving loads) but they are also designed for lateral loads of

earthquakeswind The walls are structurally integrated with roofsfloors (diaphragms)

and other lateral

2Shear wall structural systems are more stable because their supporting area (Total

cross sectional area of all shear walls) with reference to total plans area of building is

comparatively more unlike in the case of RCC framed structures

3 Walls have to resist the uplift forces caused by the pull of the wind walls have to

resist the shear forces that try to push the walls over walls have to resist the lateral force

of the wind that tries to push the walls in and pull them away from the building

4 Walls floors and roofs to the ground foundation in a direction parallel to their planes

Lateral forces caused by wind earthquake and uneven settlement loads In addition to the

weight of structure and occupants create powerful twisting (torsion) forces These forces

can literally tear (shear) a building apart Reinforcing a frame by attaching or placing a

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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7 Use connections that are not susceptible to damage in handling

Reinforcing bars steel plates dowels and bolts that project from the precast piece

will often be damaged in handling requiring repair to make them fit especially if they

are of small diameter or thickness

Connection detail that makes erection impossible

Support solution that makes erection impossible

SHEAR WALL

Shear walls are vertical elements of the horizontal force resisting system Shear walls are

constructed to counter the effects of lateral load acting on a structure In residential

construction shear walls are straight external walls that typically form a box which

provides all of the lateral support for the building

Importance of shear wall

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When shear walls are designed and constructed property and they will have the strength

and stiffness to resist the horizontal forces In building construction a rigid vertical

diaphragm capable of transferring lateral forces from exterior walls floors and roofs to

the ground foundation in a direction parallel to their planes Lateral forces caused by

wind earthquake and uneven settlement loads In addition to the weight of structure and

occupants create powerful twisting (torsion) forces These forces can literally tear (shear)

a building apart Reinforcing a frame by attaching or placing a rigid wall inside it

maintains that shape of the frame and prevents rotation at the joints shear walls are

especially important in high-rise building subjected to lateral wind and seismic forces

In the last two decades shear walls became an important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structure are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at those floors

Purpose of constructing shear walls

1 Shear walls are not only designed to resist gravityvertical loads due to its self weight

amp other living moving loads) but they are also designed for lateral loads of

earthquakeswind The walls are structurally integrated with roofsfloors (diaphragms)

and other lateral

2Shear wall structural systems are more stable because their supporting area (Total

cross sectional area of all shear walls) with reference to total plans area of building is

comparatively more unlike in the case of RCC framed structures

3 Walls have to resist the uplift forces caused by the pull of the wind walls have to

resist the shear forces that try to push the walls over walls have to resist the lateral force

of the wind that tries to push the walls in and pull them away from the building

4 Walls floors and roofs to the ground foundation in a direction parallel to their planes

Lateral forces caused by wind earthquake and uneven settlement loads In addition to the

weight of structure and occupants create powerful twisting (torsion) forces These forces

can literally tear (shear) a building apart Reinforcing a frame by attaching or placing a

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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When shear walls are designed and constructed property and they will have the strength

and stiffness to resist the horizontal forces In building construction a rigid vertical

diaphragm capable of transferring lateral forces from exterior walls floors and roofs to

the ground foundation in a direction parallel to their planes Lateral forces caused by

wind earthquake and uneven settlement loads In addition to the weight of structure and

occupants create powerful twisting (torsion) forces These forces can literally tear (shear)

a building apart Reinforcing a frame by attaching or placing a rigid wall inside it

maintains that shape of the frame and prevents rotation at the joints shear walls are

especially important in high-rise building subjected to lateral wind and seismic forces

In the last two decades shear walls became an important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structure are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at those floors

Purpose of constructing shear walls

1 Shear walls are not only designed to resist gravityvertical loads due to its self weight

amp other living moving loads) but they are also designed for lateral loads of

earthquakeswind The walls are structurally integrated with roofsfloors (diaphragms)

and other lateral

2Shear wall structural systems are more stable because their supporting area (Total

cross sectional area of all shear walls) with reference to total plans area of building is

comparatively more unlike in the case of RCC framed structures

3 Walls have to resist the uplift forces caused by the pull of the wind walls have to

resist the shear forces that try to push the walls over walls have to resist the lateral force

of the wind that tries to push the walls in and pull them away from the building

4 Walls floors and roofs to the ground foundation in a direction parallel to their planes

Lateral forces caused by wind earthquake and uneven settlement loads In addition to the

weight of structure and occupants create powerful twisting (torsion) forces These forces

can literally tear (shear) a building apart Reinforcing a frame by attaching or placing a

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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rigid wall inside it maintain the joints shear walls are especially important in high-rise

building subjected to lateral wind and seismic forces

In the last two decades shear walls became as important part of mid high rise residential

buildings As part of an earthquake resistant building design these walls are placed in

building plans reducing lateral displacements under earthquake loads So shear wall

frame structures are obtained

Shear wall buildings are usually regular in plan and in elevation However in some

buildings lower floors are used for commercial purposes and the buildings are

characterized with larger plan dimensions at these floors

Comparisons of shear wall with construction of conventional load bearing walls

Load bearing masonry is very brittle material Due to different kinds of stresses such as

shear tensileetc Caused by the earthquakes the conventional unreinforced brick

masonry collapses instantly during the unpredictable and sudden earthquakes

The RCC framed structures are slender When compared to shear wall concept of box

like three-dimensional structures though it is possible to design the earthquake resistant

RCC frame it requires extra-ordinary skills at design detailing and construction levels

Which cannot be anticipated in all types of construction projects

On the other hand even moderately designed shear wall structures not only more stable

but also comparatively quite ductile In safety terms it means that during very severe

earthquakes they will not suddenly collapse causing death of people They give enough

indicative warnings such as widening structural cracks yielding rods etc offering most

precious moment for people to run out off structures before they totally collapse

For structural purposes we consider the exterior walls as the shear resisting walls Forces

from the ceiling and roof diaphragms make their way to the outside along assumed paths

enter the walls and exit at the foundation

Forces on shear wall

Shear wall resist two types of forces

1 Shear forces

2 Uplift forces

Shear Forces

Shear forces are generated in stationary buildings by accelerations resulting from ground

movement and by external forces like wind amp waves This action creates shear forces

throughout the height of the wall between the top and bottom shear wall connections

Uplift Forces

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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Uplift forces exist on shear walls because the horizontal forces are applied to the top of

the wall These uplift forces try to lift up one end of the wall and push the other end

down In some cases the uplift force is large enough to tip the wall over Uplift forces are

greater on tall short walls uplift shear walls need hold down devices at each end when the

gravity loads cannot resist all of the uplift The hold down device then provides the

necessary uplift resistance

Classification of shear walls

1 Simple rectangular types amp flanged walls

2 Coupled shear walls

3 Rigid frame shear walls

4 Framed walls with in filled frames

5 Column supported shear walls

6 Core type shear walls

Types of shear walls

1 RC shear wall

2 Plywood shear wall

3 Mid ply shear wall

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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4 RC Hollow concrete Block masonry wall

5 Steel plate shear wall

RC shear wall

It consists of reinforced concrete walls and reinforced concrete slabs wall thickness varies

from 140 mm to 500 mm depending on the number of stories building age and thermal

insulation requirement In general these walls are continuous throughout the building

height however Some walls are discontinued as the steel front or basement level to allow

for commercial or parking spaces Floors slabs are either cast in-situ flat slabs or less

often Precast hollow core slabs Buildings are supported by concrete strip or mat

foundations the latter type is common for buildings with basements

Ply wood shear wall

Plywood is the traditional material used in the construction of shear walls the creation of

pre-fabricated shear panels have made it possible to inject strong shear assemblies into

small walls that fall at either side of a opening in a shear wall plywood shear wall consist

of

o Plywood to transfer shear forces

o Chords to resist tensioncompression generated by the over turning

moments

o Base connections to transfer shear to foundations

Midply shear wall

The midply shear wall is an improved timber shear wall that was developed by

redesigning the joints between shearing and finishing members So that the failure modes

observed in standard wall testing are virtually eliminated at lateral loads levels high

enough to cause failures in standard walls

RC Hollow concrete block masonry walls (RHCBM)

These walls are constructed by reinforcing the hollow concrete block masonry by taking

advantage of hollow spaces amp shapes of the hollow blocks It requires continuous steel

rods (reinforcement) both in the vertical amp horizontal directions at structurally critical

locations of the wall panels packed with the fresh grout concrete in the hollow spaces of

masonry bocks

RHCBC elements are designed both as load bearing walls for gravity loads and also as

shear walls for lateral seismic loads to safety withstand earthquakes

Steel plate shear wall

In general steel plate shear wall system consists of a steel plate wall boundary columns

and horizontal floor beams Together the steel plate wall and boundary columns act as a

vertical plate girder The column act as flanges of the vertical plate girder and the steel

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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plates wall act as its web The horizontal floor beams act more or less as transverse

stiffeners in a plate girder steel plate shear wall systems have been used in recent years in

highly seismic area to resist lateral loads

Thus shear walls are one of the most effective building elements in resisting lateral forces

during earthquake By constructing shear walls damages due to effect of lateral forces

due to earthquake and high winds can be minimized shear walls construction will provide

larger stiffness to the buildings there by reducing the damage to structure and its contents

Hence it is preferable to have all these prefabricate approximately of some weight very

near to the lifting capacity of the equipment

SHEAR WALL

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

WWWVIDYARTHIPLUSCOM

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

WWWVIDYARTHIPLUSCOM

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

WWWVIDYARTHIPLUSCOM

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

WWWVIDYARTHIPLUSCOM

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

WWWVIDYARTHIPLUSCOM

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particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

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3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

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3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

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WWWVIDYARTHIPLUSCOM

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5 Explain with neat sketch of the types of shear wall

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6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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Off-site fabrication

Off-Site fabrication is a process that incorporates prefabrication and pre-assembly The

process involves the design and manufacture of units or modules usually remote from the

work site and the installation at the site to form the permanent works at the site In its

fullest sense off-site fabrication requires a project strategy that will change the

orientation of the project process from construction to manufacture to installation

Examples of off-site fabrication are wall panels for homes wooden truss bridge spans

airport control stations

There are 4 main categories of Off-Site fabrication which is often also referred to as Off-

Site Construction These can be described as component (or sub-assembly) systems

penalized systems volumetric systems and modular systems Below these categories

different branches or technologies are being developed There are a vast number of

different systems on the market which fall into these categories and with recent advances

in digital design such as Building Information Modeling (BIM) the task of integrating

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

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Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

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11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

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in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

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On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

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In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

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Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

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5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

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WWWVIDYARTHIPLUSCOM

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6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

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7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

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WWWVIDYARTHIPLUSCOM

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these different systems into a construction project is becoming increasingly a digital

management proposition

Unit -1

Question with answer

Part-A-

1Define prefabrication

The term prefab can apply to any construction method where the significant part of the

construction takes place off site in a factory That produces relatively large complex

features that assembled at the site into the finished building

2What is meant by modular Coordination

Modular coordination is a concept for coordinating dimension and space for which

building and component are dimensionally it used and positioned in basic units (or)

modules

The standard specify that the module basic M = 100 mm As the basic unit be used in a

square of M

3What are the characteristics of Modular concept

I) The basic module is small in terms of add size in order to provide design flexibility

yet large enough to promote simplification in the component variation in sizes

II) Industry friendly features that not only for manufacturing but also the transportation

and assembly requirements

III) Internationally accepted to support international market

4 Write out the advantages amp disadvantages of prefabrication

I) Self supporting readymade components are used so the need for formwork shuttering

and scaffolding is greatly reduced

II) On-site construction and condition is minimized

III) Less waste may occur

Disadvantages

I)Careful handling of prefabricated components such as concrete panels (or) steel and

glass Panels is reduced

II) Similarly leaks can form at joints is prefabricated component

5) Define the term Off-site fabrication

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

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Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Off-site fabrication is the process that incorporates prefabrication and preassemble the

process involves the design and manufacture of units usually remote from the work site

and the installation at the site to form the permanent work at the site

6) Write short note on Production process

The production of concrete blocks consists of four basic process They are

1) Mixing

2) Moulding

3) Curing

4) Cubing

7) List out the limitations of prefabrication

I) Extra reinforcement is required to take care of handling and erection stresses

II) Temporary props may be required in some cases before the un-site concrete joints

achieve strength

III) The cracks may develop at the joints between the precart in ndashsite concrete due to

shrinkage and temperature stresses To overcome them extra steel is required across

joint

8) What are all the Prefab materials

Structural insulated panels (SIPs)

Insulating concrete forms (ICFS)

Prefab foundation system

Steel framing

Concrete framing

Large - modular system

9) Insulating concrete forms

Insulating concrete forms (ICE) are a prefab construction material consisting of hollow

EPS foam blocks that are stacked and glued together on-site creating the form that is

filled with reinforcing bars and concrete

10) Write short note on Principles of MC Concept

The principle objective of implanting MC is to improve productivity through the

reduction of wastages in the production installation process to improve quality in the

construction industry and to encourage an open system

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

WWWVIDYARTHIPLUSCOM

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Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

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7 Explain in detail various design consideration in the design of precast construction

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WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

11 Define shear wall

These are simple type and these shear walls under forces and horizontal shear along its

length are subjected to bending and shear To resist these forces the uniform

distribution of steel along its length is used in simple shear walls

12 Different classification of shear walls

1) Plain rectangular shear wall

2) Bar bell type

3) Framed shear wall

4) Coupled shear wall

5) Care type

13What is Modular Coordination

Modular coordination or MC is a dimensional system It is a dimension and space

coordination concept in which building and components are placed at their

designations based on the unit

14 How dimensional coordination is helpful in prefabricated structures

Building production is the organization and management of the plans equipment

materials and labour involved in the construction of a building while at the same time

complying with all codes rules and contractual stipulations The procedure should be

designed to run efficiently to keep the costs low and to allow returns on the

investment to be realized as early as possible

15 Explain the term basic module

Modular are terms that usually refer to upscale housing that can be any combination

of pre-engineered home parts that re delivered to the building site ready to be

assembled in a quick manner

16 What are the factors to consider in transporting of prefabricated structures

Transport device being movable from the input end to the output end of the production

line through a series of workstations said building unit being fabricated on an upper

surface of said flatbed said flatbed having an anti-friction surface on the upper surface

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WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

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WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

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Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

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15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

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2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

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6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

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7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

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thereof for permitting sliding movement of said building unit relative to said transport

device

17 Explain the role of shear connectors in pre fabricated structures

Shear connectors may be spaced uniformly between the sections of maximum and zero

moment Shear connectors should have at least 1 in (254 mm) of concrete cover in all

directions and unless studs are located directly over the web stud diameters may not

exceed 25 times the beam-flange thickness With heavy concentrated loads the uniform

spacing of shear connectors may not be sufficient between a concentrated load and the

nearest point of zero moment

18 What are the special material properties in of prefabricated structures

Quicktoassemble

Cost-effective

Portablemovable

Strong

Water proof Moisture proof

Fire Resistant

19 What are the types of shear walls

Vertical Offset of Shear Walls

Stiffness shear wall

Steel shear wall

20 Write short notes on prefabrication

Prefabrication is the practice of assembling components of a structure in a factory or

other manufacturing site and transporting complete assemblies or sub-assemblies to

the construction site where the structure is to be located prefabrication in

architectural construction a technique whereby large units of a building are produced

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

in factories to be assembled ready-made on the building site The technique permits

the speedy erection of very large structures

21 Write any two advantages of prefabrication construction

Self-supporting ready-made components are used so the need for formwork

shuttering and scaffolding is greatly reduced

Construction time is reduced and buildings are completed sooner allowing an

earlier return of the capital invested

22 Define the term module

23 Write short notes on shear wall

A shear wall is a wall which is designed to resist shear the lateral force which causes

the bulk of damage in earthquakes

24 Write any two prefabrication problem of materials

Non availability of materials

Economy

25 Write the types of Derricks

A derrick is a lifting device composed of one mast or pole which is hinged freely at

the bottom It is controlled by lines powered by some means such as man-hauling or

motors so that the pole can move in all four directions

Hallen Derrick

Velle Derrick

Stuumllcken Derrick

26 What are the advantages of prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

On-site construction and congestion is minimized

Quality control can be easier in a factory assembly line setting than a construction

site setting

Prefabrication can be located where skilled labour is more readily available and

costs of labour power materials space and overheads are lower

Time spent in bad weather or hazardous environments at the construction site is

minimised

27 What are the safety factors to be considered in designing

28 Explain about the location of shear wall

Lateral forces caused by wind earthquake and uneven settlement loads in addition to

the weight of structure and occupants create powerful twisting (torsional) forces

These forces can literally tear (shear) a building apart Reinforcing a frame by

attaching or placing a rigid wall inside it maintains the shape of the frame and

prevents rotation at the joints Shear walls are especially important in high-rise

buildings subject to lateral wind and seismic forces

29 What are the lateral loads in a building Live load

Wind load

Earthquake load 30What are the lateral load resisting elements in a building (AUC NovDec 2013) Vertical Elements

Moment

Resisting Frames

Walls

Bearing walls Shear Walls Structural Walls

Gravity Frame + Walls

ldquoDualrdquo System (Frame + Wall)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Vertical Truss

Tube System

Bundled

Tube System FloorDiaphragm

Foundation

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Part-B

1Explain Modular Coordination in detail

Modular coordination means the interdependent arrangement of a dimension based on a

primary value accepted as a module The strict observance of rules of modular

coordination facilitated

1 Assembly of single components into large components

2 Fewest possible different types of component

3 Minimum wastage of cutting needed

Modular coordination is the basis for a standardization of a mass production of

component A

set of rules would be adequate for meeting the requirements of conventional and

prefabricated construction These rules are adaptable for

a The planning grid in both directions of the horizontal plan shall be

1 3M for residential and institutional buildings

2 For industrial buildings

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

15M for spans up to 12m

30M for spans between 12m and 18m

60M for spans over 18m

The centre lines of load bearing walls shall coincide with the grid lines

b In case of external walls the grid lines shall coincide with the centre line of the wall or

a line on the wall 5 cm from the internal face of the wall

C The planning module in the vertical direction shall be 1M up to and including a ht of

28M

d Preferred increments for the still heights doors windows and other fenestration shall

be

1M

e In case of internal columns the grid lines shall coincide with the centre lines of

columns In case of external columns the grid lines shall coincide with the centre lines of

the columns in the storey or a line in the column from the internal face of the column in

the topmost storey A basic module can be represented as module and for larger project

modules are represented a Mp

For eg For a project module in horizontal coordination the component can be of 30cm

and for vertical component size be of 10cm

The storey height is fixed between finished floor levels as 28m and if the thickness of

slab is lt15cm storey height is fixed as 27m The centre distance between the load

bearing walls can be chose from a set of modules The use of other dimensions is not

allowed

In the design of a building modular grid can be used consisting of parallel line spaced at

a value of module M or Mp and a grid line chosen as a base for setting out a part of a

building becomes a modular axis In the fig (a) a typical grid is chosen for load bearing

walls without duct The interior walls are placed so that their centre lines coincide with

the modular axis In the fig (b) a grid is shown for load bearing walls with hollow ducts

in between The centre line of the grid is found by deducting the size of duct

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

2Systems of prefabrication

System is referred to a particular method of construction of buildings using the

prefabricated components which are inter related in functions and are produced to a set of

instructions With certain constraints several plans are possible using the same set of

components the degree of flexibility varies from system to system However in all the

systems there is a certain order and discipline The system of prefabricated construction

depends on the extend of the use of prefab components their characteristics to be

considered in devising a system

i Intensified usage of spaces

ii Straight and simple walling scheme

iii Limited sizes and numbers of components

iv Limited opening in bearing walls

v Regulated locations of partitions

vi Standardized service and stair units

vii Limited sizes of doors and windows with regulated positions

viii Structural clarity and efficiency

ix Suitability for adoption in low rise and high rise blocks

x Ease of manufacturing storing and transporting

xi Speed and ease of erection

xii Simple jointing system

a) Based on Disuniting of member

b) Based on the construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Based on Disuniting of member

1 System consisting of linear member disunited at joints

2 System for prefabricates of entire rigid frame

3 System consisting of ITU of straight members disunited at points of minimum

moment

4 Two hinged and three hinged arches

System consisting of linear member disunited at joints

Advantage

Disuniting at joints gives linear member This means that a great advantage and facilitates

from the view point manufacture and assembly

Disadvantage

1 Joints are at corners ie at points of maximum moment values so forming the joint is

difficult

2 Joints must be over dimensioned to cope with in-situ concreting And one alternate

solution to replace moment resistant joints by hinged connection

System for prefabricates of entire rigid frame

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

In this system to reduce the no of joints and to precast larger numbers I one piece leads

to the prefabrication of entire frame Production of the frames does not cause any

particular trouble but the hoisting is more difficult and requires careful preparation The

stress distribution of straight members during hoisting is in general statistically

determinate

Advantage

1 It is ideal for site prefabrication

2 Small number of joints so rapid prefabrication work is possible

3 Suitable for long walls consisting of great number of uniform frames

System consisting of ITU of straight members disunited at points of minimum

moment

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Another method of disuniting of structures is by division into different membranes at

points where the moments are thin or smallest This method is called as lambda method

Using this method hinge joints are made

Advantage

1 Functions are made at points of minimum moments or at points of contra flexure

2 Disuniting the main girder in this manner makes the application of different skylights

possible

Disadvantage

1 Hosting and temperature bracing of L joined asymmetric frame members is

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

particularly complicated

2 Temperature resting of frame member on each other necessitates the use of

cantilevers having half depth and proper forming of this cause difficulty

Two hinged and three hinged arches

Arched structures are normally two hinged and three hinged arches Arched structures are

normally used for bridging span more than 20-25m Their production and placing is more

difficult than straight members Arch can be two hinged and three hinged but they can

also be fixed at footings and can be constructed with or without tie

These members are generally precast and assembled in statistically determinant three

hinged variance and middle hinge is only eliminated after placing is finished The

reinforcing bars protruding both sides are welded together and the joint between the

members is filled in with insitu concrete

Arch structure can be precast in either vertical or horizontal positions In the first case

shuttering made of timber or concrete is required having the same curvature s the arch

itself

The prefabrication of larger arches in the horizontal position is found to be more

economical

The construction of arch trusses can be properly carried out in the horizontal position

only

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Methods of prefabrication

Site prefabrication- for large prefabricates

Plant prefabrication- large scale production

Site prefabrication

1 The RC members are produced t the site in the open air chiefly in the open air or in

the temporary sheds

2 The difficulties in construction in general are felt in this mechanization can case

3 Mechanization cannot be of such high degree as site PF is done for smaller duration

of time

4 When the pre fabricates are of large size it is difficult to transport the pre fabricates to

the site

5 In comparison with plant prefabrication transportation of the members are not needed

As large members are not transported the design and weight of the prefabricates are not

limited

Plant prefabrication

1 The members produced are to be transported t the place of construction this accounts

for about 10-15 of the cost of production and assembling

2 Certain restriction is made in the dimension of prefabrication leading to restraints in

the design and development of prefabrication

3 Prefabrication is appropriate for mass production for manufacture of standardized

members

4 Needs costly materials for batching and production

5 This method is most suited in the case of small prefabricates which are to be

prefabricated in very large number

Plant prefabrication is done under permanent plant or factories It is done under the

covered roof so the effect of weather does not affect the work So the quality and strength

of the members can be improved considerably Plant prefabrication reduces the cost of

prefabrication if the number of prefabricate needed is more

Dimensions of prefabricate

There are 3 commonly known dimension for the prefabricates

1 The design of the erection dimension governing the dimensional coordination of the

prefabricates

2 Theoretical dimension

3 The actual dimension of the element when delivered the design dimension should be a

multiple of a basic module size m or of a module lap

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

Production of prefabricates

Production techniques involved are

1 Stand method

2 Conveyor method or line method

3 Aggregate method

Stand Method

In this method the prefabrication mature where they are moulded while the production

teams moves to successive stands The bed on which prefabricates are cast may be fixed

or

movable Tilting forms are often used and in this method steam curing is generally done

Conveyor belt method

The whole production is split up in to series operations carried out at separate successive

and permanent points served by specialized teams The movement of the mould or

prefabricate one point to other vary by means of conveyor belt trolleys

The rigid steel forms are assembled at station 1 where they are mould oil to reduce the

adhesion of concrete The conveyor moves front 1 to 2 where prestressing wires are fixed

amp in the next station anchoring of the wires is carried out The prepared mould is then

carried to the station 1ie casting station After casting it is shifted to the vibrating table amp

finally stacked station 5 for setting After that it is passed through tunnel autoclave for

curing After steam curing move too station 7 for demoulding amp is finally stacked 8

Aggregate method

In the aggregate method aggregate describes large complex permanently installed

machines amp mechanical appliances which carry out most of the separate operations

involved in the casting of the concrete composition The stand is operated by a permanent

team amp the only move the prefabricate makes is to the maturing point

Aggregate method is used in the production of multi duct hollow floor panel in Poland

At production point the reinforcement is fixed in the form amp remote controlled

aggregate(machine)inserts the duct formers castamp vibrates the concrete floats the top

of the floor The prepared prefabricate then move to the autoclave chamber in which

hardening of concrete is accelerate In many factories combined technology are employed

when complex prefabricate are required

Advantages

1The stand technique is the most flexible one It is used in varying degrees of

mechanization in all kinds of prefabricate factories

2It is simple amp less capital is required It can be used for field prefabricate also

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

3Aggregate method is used for large scale production in which case number of

machineries is required

4 Explain specific requirements in layout of of prefabricated plants

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

5 Explain with neat sketch of the types of shear wall

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

6 What is the code use for prefabricated structures

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

7 Explain in detail various design consideration in the design of precast construction

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)

WWWVIDYARTHIPLUSCOM

WWWVIDYARTHIPLUSCOM KBALAJI 119820119812 (119852119853119851119854119836119853)