Modern Building Materials and Technology

Bibhuti Bhushan Bhardwaj a

, Azaz Ahmed b

Department of Civil Engg., School of Engineering, Tezpur University, Napaam 784028, Tezpur, Assam, India

Email: a bibhuti_cib09@agnee.tezu.ernet.in, b azaz_cib09@agnee.tezu.ernet.in

Abstract

The appearance, component materials, energy efficiency and environmental impact of habitable

structures have changed dramatically over recent years due in large part to the successful stand-

ardization of new materials, processes and technologies. Modern building materials are gaining

great importance in the construction technologies in different field. From the construction of

small houses to large skyscrapers it is gathering unbelievable universal acceptance. A multina-

tional corporation called “Dow Corning” headquartered in Midland, Michigan, USA specializes

in silicon and silicone based technology offering more than 7,000 products and services. Fire-

proofing, soundproofing technologies are being used in modern buildings in developed as well

as in developing countries widely. Also since the 1990s, ASTM (American Society for testing

Materials) has been playing a significant role in the production of modern building materials by

taking test and grading the standard and quality of the materials.

Keywords: Skyscraper, Dow Corning, ASTM, Framework, Quonset hut, Prefabrication, Vortex

shedding, Damper, Winslow effect.

Introduction

In order to compose a civil structure today, it takes more than just meeting the needs of function-

ality and load carrying capacity under static loads. There is an increasing demand for slender,

wide spanned structures with high adaptability to changes in use. Yet another aim is the reduc-

tion of structural mass for economic reasons. Aesthetically beautiful buildings require both a

mixture of beauty and workability. Appealing structures of the modern world such as the Sydney

Opera house, the Burj-Al-Arab in Dubai, the Taipei 101, infinity tower etc have set up new land-

marks in the Construction industry. Many of the old building materials and orthodox techniques

failed to comply with the standards setup for such revolutionary structures. Standards bolster ad-

vances in construction technologies. The appearance, component materials, energy efficiency

and environmental impact of habitable structures has changed dramatically over recent years due

in large part to the successful standardization of new materials, processes and technologies. As

expected, as the new structures are soaring towards the sky, more and more challenges are con-

fronted with. Factors such as earthquake resistance, resistance to vortex shedding, firm founda-

tions, quality of soil, fire proofing, cost effectiveness etc are given more priority than never be-

fore.

Types

They are the materials which have the capability to respond to changes in their condition or the

environment to which they are exposed, in a useful and usually repetitive manner. They are

called by other names such as-

Intelligent materials, adoptive materials or active materials.

The devices that are made using smart materials are called Smart Devices. Similarly the systems

and structures that have incorporated smart materials are called Smart Systems and Smart Struc-

tures. In other words the complexity increases from smart materials to smart structures. A smart

material or an active material gives a unique output for a well defined input. The input may be in

the form of mechanical stress / strain, electrical / magnetic field or changes in temperature.

Based on input and output, the smart materials are classified as follows.

1. Shape Memory Alloys (SMAs)

The term shape memory refers to the ability of certain alloys (Ni – Ti, Cu – Al – Zn etc.) to un -

dergo large strains, while recovering their initial configuration at the end of the deformation pro-

cess spontaneously or by heating without any residual deformation .The particular properties of

SMA’s are strictly associated to a solid-solid phase transformation which can be thermal or

stress induced. Currently, SMAs are mainly applied in medical sciences, electrical, aerospace

and mechanical engineering and also can open new applications in civil engineering specifically

in seismic protection of buildings.

Shape memory alloys have great potential to enhance civil engineering structures. Pre-existing

and new applications in the fields of damping, active vibration control and pre-stressing or post-

tensioning of structures with fibres and tendons are being reviewed with regard to civil engineer-

ing. Properties such as repeated absorption of large amounts of strain energy under loading

without permanent deformation, possibility to obtain a wide range of cyclic behaviour from sup-

plemental and fully re-entering to highly dissipating-by simply varying the number and/or the

characteristics of SMA components, usable strain range of 70%, extraordinary fatigue resist-

ance under large strain cycles enable them for civil engineering applications.

In the fig. 1 SMAs are being shown [1].

Fig. 1: Shape Memory Alloys (Source

http://thefutureofthings.com/news/18/adaptive-aerodynamics-using-smart-

materials.html)

2. Magnetostrictive Materials

Magnetostriction is the changing of a material's physical dimensions in response to changing its

magnetization. In other words, a magnetostrictive material will change shape when it is subjec-

ted to a magnetic field.  Most ferromagnetic materials exhibit some measurable magnetostric-

tion. The highest room temperature magnetostriction of a pure element is that of Cobalt (Co)

which saturates at 60 micro strain. Fortunately, by alloying elements one can achieve "giant"

magnetostriction under relatively small fields. The highest known magnetostriction are those of

cubic laves phase iron alloys containing the rare earth elements Dysprosium (Dy), or Terbium

(Tb); DyFe2, and TbFe2. However, these materials have tremendous magnetic anisotropy which

necessitates a very large magnetic field to drive the magnetostriction.

Other examples include Terfenol-D, (an alloy of Iron and Terbium) [2].

3. Piezoelectric Materials

Simply stated, piezoelectric materials produce a voltage in response to an applied force, usually

a uniaxial compressive force. Similarly, a change in dimensions can be induced by the applica-

tion of a voltage to a piezoelectric material. In fig. 2 examples of piezoelectric materials are be-

ing shown [3].

Fig. 2: Piezoelectric Material (source:

http://webdocs.cs.ualberta.ca/~database/MEMS/sma_mems/smrt.html)

4. Electro Rheological Fluids

Electro Rheological (ER) fluids are suspensions of extremely fine non-conducting particles (up

to 50 micrometres diameter) in an electrically insulating fluid. The apparent viscosity of these

fluids changes reversibly by an order of up to 100,000 in response to an electric field. For ex-

ample, a typical ER fluid can go from the consistency of a liquid to that of a gel, and back, with

response times on the order of milliseconds. The effect is sometimes called the Winslow effect,

after its discoverer the American inventor Willis Winslow, who obtained a US patent on the ef-

fect in 1947 [1].

5. Carbon Fibre Reinforced Concrete (CFRC)

Its ability to conduct electricity and most importantly, capacity to change its conductivity  with

mechanical stress  makes a promising material  for smart structures. It is evolved as a part of

DRC technology (Densified Reinforced Composites).The high density coupled with a choice of

fibres ranging from stainless steel to chopped carbon and Kevlar, applied under high pressure

gives the product with outstanding qualities as per DRC technology. This technology makes it

possible to produce surfaces with strength and durability superior to metals and plastics [4].

6. Smart Concrete

Smart concrete was developed Dr. Deborah D.L. Chung from State University of New York at

Buffalo. Smart concrete is reinforced by carbon fibre as much as 0.2% to 0.5% of volume to in-

crease its sense ability to strain or stress while still has good mechanical properties. By adding

small amount of short carbon fibre into concrete with a conventional concrete mixer, the elec-

trical resistance of concrete can be increased in response to strain or stress. As the concrete is

deformed or stressed, the contact between the fibre and cement matrix is affected, thereby affect -

ing the volume electrical resistivity of the concrete. Strain is detected through measurement of

the electrical resistance. So, the smart concrete has the ability to sense tiny structural flaws be-

fore they become significant, which could be used in monitoring the internal condition of struc-

tures and following an earthquake. In addition, the presence of the carbon fibres also controls the

cracking so that the cracks do not propagate catastrophically, as in the case of conventional con-

crete [4].

7. Metal

Metal is used as structural framework for larger buildings such as skyscrapers, or as an external

surface covering. There are many types of metals used for building. Steel is a metal alloy whose

major component is iron, and is the usual choice for metal structural building materials. It is

strong, flexible, and if refined well and/or treated lasts a long time. Corrosion is metal's prime

enemy when it comes to longevity. The lower density and better corrosion resistance of alu-

minium alloys and tin sometimes overcome their greater cost. Brass was more common in the

past, but is usually restricted to specific uses or specialty items today. Metal figures quite prom-

inently in prefabricated structures such as the Quonset hut, and can be seen used in most cosmo-

politan cities. It requires a great deal of human labour to produce metal, especially in the large

amounts needed for the building industries. Other metals used include titanium, chrome, gold,

silver. Titanium can be used for structural purposes, but it is much more expensive than steel.

Chrome, gold, and silver are used as decoration, because these materials are expensive and lack

structural qualities such as tensile strength or hardness [5].

8. Glass

In modern structures, glass is also used as a construction material for outer beauty of the struc-

ture. Using clear windows in houses has been known from the days glass since glass was inven-

ted but now glass is used to cover the whole façade of a building as a curtain wall to cover open

roof known as space frames for big halls and lobbies. Glass needs some sort of holding mechan-

ism and suspensions to stay longer as glass itself is very delicate and easy to be broken material.

Other than all the above mentioned materials, materials like Ice are use to construct Eskimos in

ice lands.

Natural materials are still considered best in some regions for the purpose of construction. Fabric

is used to construct tents and tent houses. Plastic and foam is also used in construction for differ-

ent purposes [5].

9. Plastic

The term plastic covers a range of synthetic or semi-synthetic organic condensation or polymer-

ization products that can be moulded or extruded into objects or films or fibres. Their name is

derived from the fact that in their semi-liquid state they are malleable, or have the property of

plasticity. Plastics vary immensely in heat tolerance, hardness, and resiliency. Combined with

this adaptability, the general uniformity of composition and lightness of plastics ensures their use

in almost all industrial applications today [5].

10. Foam

More recently synthetic polystyrene or polyurethane foam has been used in combination with

structural materials, such as concrete. It is light weight, easily shaped and an excellent insulator.

It is usually used as part of a structural insulated panel where the foam is sandwiched between

wood and cement or insulated concrete forms where concrete is sandwiched between two layers

of foam [5].

Some Modern Technologies

Soundproofing

Specialty Vinyl for Soundproofing and Other Noise Stopping Materials

Frequently called Mass Loaded Vinyl (MLV), these materials certainly have their place and can

be used in many different ways to stop the transfer of noise. Sometimes this is described as a

panacea (cure all – solve all) and it is not.

Always it has to be remembered the principle of mass: if it does not weigh much it will not stop

much. Also people should realize that adding together several high mass layers does not help

either.

Insulation or How to Fill the Wall Cavities

Stuffing the walls with insulation is bad. People are taking out the air that is helpful in insulating

and stopping noise.

Using the pink stuff is easiest and economical. It works okay. Most insulation does very little to

help noise reduction [6].

Lead Lined Sheetrock

Uses about a 1/8 inch sheet of lead glued to one side of the sheetrock and installed with the lead

facing the studs.

This is an excellent noise reducer, but can cost ` 6250-12500 per piece of sheetrock [6].

Fireproofing

Fireproofing, a passive fire protection measure, refers to the act of making materials or structures

more resistant to fire, or to those materials themselves, or the act of applying such materials. Ap-

plying a certification listed fireproofing system to certain structures allows these to have a fire-

resistance rating. The term fireproof does not necessarily mean that an item cannot ever burn: It

relates to measured performance under specific conditions of testing and evaluation. Fireproof-

ing does not allow treated items to be entirely unaffected by any fire, as conventional materials

are not immune to the effects of fire at a sufficient intensity and/or duration.

Asbestos was one material historically used for fireproofing, either on its own, or together with

binders such as cement, either in sprayed form or in pressed sheets, or as additives to a variety of

materials and products, including fabrics for protective clothing and building materials. Because

the material has proven to cause cancer in the long run, a large removal and replacement busi-

ness has been established. Endothermic materials have also been used to a large extent and are

still in use today, such as gypsum, concrete and other cementitious products. More highly

evolved versions of these are used in aerodynamics, intercontinental ballistic missiles (ICBMs)

and re-entry vehicles, such as the space shuttles.

Among the conventional materials, purpose-designed spray fireproofing plasters have become

abundantly available the world over. The inorganic methods include:

Gypsum plasters

Cementious plasters

Fibrous plasters

The industry considers gypsum-based plasters to be "cementious", even though these contain no

Portland cement, or calcium alumina cement. Cementious plasters that contain Portland cement

have been traditionally lightened by the use of inorganic lightweight aggregates, such as vermi-

culite and perlite.

Gypsum plasters have been lightened by using chemical additives to create bubbles that displace

solids, thus reducing the bulk density. Also, lightweight polystyrene beads have been mixed into

the plasters at the factory in an effort to reduce the density, which generally results in a more ef -

fective insulation at a lower cost. The resulting plaster has qualified to the A2 combustibility rat -

ing as per DIN4102. Fibrous plasters, containing either mineral-wool or ceramic fibres tend to

simply entrain more air, thus displacing the heavy fibres. On-site cost reduction efforts, at times

purposely contravening the requirements of the certification listing, can further enhance such

displacement of solids. This has resulted in architects' specifying the use of on-site testing of

proper densities to ensure the products installed meet the certification listings employed for each

installed configuration, because excessively light inorganic fireproofing does not provide ad-

equate protection and are thus in violation of the listings.

New materials based on organic chemistry are gaining in popularity for a variety of reasons. In

land-based construction, thin-film intumescents have become more widely used. Unlike their

inorganic competitors, thin-film intumescents are installed like paint, except that the purpose is

to achieve a certain thickness, not just to apply a different colour, and do not require the conceal-

ment of structural steel elements such as I-beams and columns. Care must be taken to ensure that

such products are protected from atmospheric moisture and operational heat, which can ad-

versely affect these organic, covalently bound products. The use of DIBt approved products,

which mandates testing of the effects of ageing, is prudent.

Thicker intumescent and endothermic resin systems tend to use an oil basis (usually epoxy),

which, when exposed to fire, creates so much smoke, that even though these products provide

enough heat flow retardation towards the substrate, they tend to be banned from use inside of

buildings because of the smoke they develop when subjected to fire, and are used mainly in ex-

terior construction, such as LPG vessels, vessel skirts and pipe bridges in oil refineries, chemical

plants and offshore oil and gas platforms.

Proprietary boards and sheets, made of gypsum, calcium silicate, vermiculite, perlite, mechanic-

ally bonded composite boards made of punched sheet-metal and cellulose reinforced concrete

(Dura Steel) have all been used to clad items for increased fire-resistance. Cladding is tradition-

ally much more popular and organised in Europe than in North America. Fringe methods have

also included intumescent tapes and sheets, as well as endothermically treated ceramic fibre

sheets and roll materials. The latter work well but are not particularly popular due to cost reas-

ons.

Ordinary ceramic fibre, typically encased in thin aluminium foil is often used to protect pressur-

isation ductwork and grease ducts in North America. Such mineral wool (rock wool) wraps have

been used in Europe for decades more than in North America. European construction sites tend

to use much less expensive mineral wool wraps for duct fireproofing. All are qualified to the

same test regime: ISO6944, with the exception that systems qualified for the North America

market also undergo a hose-stream test immediately following the fire exposure in order to val-

idate the fire stop portion of the system [7].

Natural Fibre Reinforcement of Large-Scale Composite Polymer Panels

Recently, natural fibres (NF) have been investigated as filler materials capable of serving as loc-

alized tensile reinforcement and volume fillers within several types of polymer matrices. A num-

ber of natural fibres have been under continued investigation for use in natural fibre reinforced

polymer composites (NFRC); including wood fibre, jute, sisal, kenaf, flax, wheat straw and bam-

boo. These fibres have been coupled in a matrix primarily composed of two commodity plastic

matrix materials: polyethylene (PE) and polystyrene (PS). While specific mechanical properties

of natural fibres vary according to the particular fibre, the overall performance of natural fibres

lies within a relatively tight range as a result of similar molecular composition. An increasing

amount of interest has developed over the past few years for NFRCs because of their ease of

production, subsequent increase in productivity, cost reduction, lower density and weight and

use of renewable resources. The automobile industry has begun to apply NFRCs in a variety of

exterior and interior panel applications. The significant weight savings and the ease and low cost

of the raw constituent materials have made NFRCs an attractive alternative material to glass and

carbon fibre reinforced polymer composites. However, further research needs to address signi-

ficant material and production obstacles before commercially available NFRCs are widely used

in architectural and civil works [8].

Earthquake Resistant Building Technology

Ground shaking from earthquakes can collapse buildings and bridges; disrupt gas, electric, and

phone services; and sometimes trigger landslides, avalanches, flash floods, fires, and huge, de-

structive ocean waves (tsunamis). Buildings with foundations resting on unconsolidated landfill

and other unstable soil, and trailers and homes not tied to their foundations are at risk because

they can be shaken off their mountings during an earthquake. When an earthquake occurs in a

populated area, it may cause deaths and injuries and extensive property damage. It is for this

reason that it is often said,

“Earthquake don’t kill people, buildings do.”

Earthquake resistant building design philosophy

a) Under minor but frequent shaking, the main members of the buildings that carry vertical and

horizontal forces should not be damaged; however buildings parts that do not carry load may

sustain repairable damage.

b) Under moderate but occasional shaking, the main members may sustain repairable damage,

while the other parts that do not carry load may sustain repairable damage.

c) Under strong but rare shaking, the main members may sustain severe damage, but the build-

ing should not collapse.

Protection from Earthquakes

There are various new techniques which help in reducing the impact of earthquake forces on

buildings. Most of these techniques are expensive to implement.

Here is a list of Earthquake Resistant Techniques:

1. Base Isolation for Earthquake Resistance

The concept of base isolation is explained through an example building resting on frictionless

rollers. When the ground shakes, the rollers freely roll, but the building above does not move.

Thus, no force is transferred to the building due to the shaking of the ground; simply, the build-

ing does not experience the earthquake. Now, if the same building is rested on the flexible pads

that offer resistance against lateral movements, then some effect of the ground shaking will be

transferred to the building above. If the flexible pads are properly chosen, the forces induced by

ground shaking can be a few times smaller than that experienced by the building built directly on

ground, namely a fixed base building. The flexible pads are called base-isolators, whereas the

structures protected by means of these devices are called base-isolated buildings.

2. Energy Dissipation Devices for Earthquake Resistance

Another approach for controlling seismic damage in buildings and improving their seismic per-

formance is by installing Seismic Dampers in place of structural elements, such as diagonal

braces. These dampers act like the hydraulic shock absorbers in cars as“ much of the sudden

jerks are absorbed in the hydraulic fluids and only little is transmitted above to the chassis of the

car. When seismic energy is transmitted through them, dampers absorb part of it, and thus damp

the motion of the building.

3. Active Control Devices for Earthquake Resistance

The system consists of three basic elements:

a. Sensors to measure external excitation and/or structural response.

b. Computer hardware and software to compute control forces on the basis of observed excita-

tion and/or structural response.

c. Actuators to provide the necessary control forces.

Thus in active system has to necessarily have an external energy input to drive the actuators. On

the other hand passive systems do not required external energy and their efficiency depends on

tunings of system to expected excitation and structural behaviour. As a result, the passive sys-

tems are effective only for the modes of the vibrations for which these are tuned. Thus the ad-

vantage of an active system lies in its much wider range of applicability since the control forces

are worked out on the basis of actual excitation and structural behaviour. In the active system

when only external excitation is measured system is said to be in open-looped. However when

the structural response is used as input, the system is in closed loop control.

These techniques have been successfully employed in many projects across the world. They are

most widely used in Japan. These techniques are also being used in earthquake prone areas of

California, Indonesia and other such places [9].

Construction and materials used in Skyscrapers

Reinforced concrete is one important component of skyscrapers. It consists of concrete (a mix-

ture of water, cement powder, and aggregate consisting of gravel or sand) poured around a grid

work of steel rods (called rebar) that will strengthen the dried concrete against bending motion

caused by the wind. Concrete is inherently strong under compressive forces; however, the

enormous projected weight of the PETRONAS Towers led designers to specify a new type of

concrete that was more than twice as strong as usual. This high-strength material was achieved

by adding very fine particles to the usual concrete ingredients; the increased surface area of these

tiny particles produced a stronger bond.

The other primary raw material for skyscraper construction is steel, which is an alloy of iron and

carbon. Nearby buildings often limit the amount of space available for construction activity and

supply storage, so steel beams of specified sizes and shapes are delivered to the site just as they

are needed for placement. Before delivery, the beams are coated with a mixture of plaster

and vermiculite (mica that has been heat-expanded to form sponge-like particles) to protect them

from corrosion and heat. After each beam is welded into place, the fresh joints are sprayed with

the same coating material. An additional layer of insulation, such as fibreglass batting covered

with aluminium foil, may then be wrapped around the beams.

To maximize the best qualities of concrete and steel, they are often used together in skyscraper

construction. For example, a support column may be formed by pouring concrete around a steel

beam.

A variety of materials are used to cover the skyscraper's frame. Known as "cladding," the sheets

that form the exterior walls may consist of glass, metals, such as aluminium or stainless steel, or

masonry materials, such as granite, marble, or limestone [10].

Case Studies

To have a an idea about how and where the modern building materials are being used in the con-

struction of different modern buildings, we have given the examples of following modern build-

ings and materials as well as technologies involved.

1. Burj Khalifa

The building Burj Khalifa, also known formerly as Burj Dubai, located in Dubai, United Arab

Emirates is presently holding the title of tallest building in the world. Its construction started in

the year of 2004 and was finished in 2010. The height of its roof is 828 metre, top floor being at

a height of 621.3 metre from ground.

• With a budget for this project exceeding ` 7500 crores, the final height of the spectacular Burj

Khalifa skyscraper soars to 828m above ground level, holding the record for being the world’s

tallest building and also for the highest installation of an aluminium and glass facade

• This iconic project has overcome the greatest of challenges and technical difficulties, not least

of which are the wind forces dominating the structural design of the tower, the logistics of mov-

ing men and materials at extreme heights and construction of the building envelope

• A total of 103,000 square metres of glass was used in the cladding panels which are incorpor-

ated into a total facade area of 132,190 square metres

• These advanced cladding panels maximise resistance against heat transmission from the sun

and save energy through the use of sophisticated engineering techniques which include high per-

formance reflective glazing

• Managing the internal pressure foreseen within the insulating glass units due to the high alti -

tude culminated in the specification of Dow Corning 3362 Silicone Insulating Glass Sealant

• Dow Corning 993 Silicone Structural Glazing Sealant was specified to bring additional security

to the insulating glass units which were mechanically fixed to the superstructure

• Dow Corning 798 Cold and Clean room Silicone Sealant was specified for sealing the exclus-

ive bathrooms within the prestigious apartments. In fig. 3 the building Burj Khalifa is shown

[11].

Fig.3: Burj Khalifa (source: http://yeinjee.com/2010/burj-khalifa-dubai-facts-

figures/)

As with any construction in the Middle East, Dow Corning’s technical experts were confronted

with testing and specifying products that are able to withstand the rigours of high temperature,

ultra-violet light, seismic activity and inclement weather conditions including sandstorms and

high winds. Special mixes of concrete are made to withstand the extreme pressures of the

massive building weight; as is typical with reinforced concrete construction, each batch of con-

crete used was tested to ensure it could withstand certain pressures. The consistency of the con-

crete used in the project was essential. It was difficult to create a concrete that could withstand

both the thousands of tonnes bearing down on it and Persian Gulf temperatures that can reach 50

°C. To combat this problem, the concrete was not poured during the day. Instead, during the

summer months ice was added to the mixture and it was poured at night when the air is cooler

and the humidity is higher. A cooler concrete mixture cures evenly throughout and is therefore

less likely to set too quickly and crack.

2. Burj-Al-Arab

Burj-Al-Arab situated in Dubai, UAE is currently holding the tallest hotel in the world. The

tallest sea-based hotel in the world at a height of 321 metres, the Burj Al Arab Hotel is a land-

mark icon on the Dubai skyline. An artificial island was created to support this architectural and

technical marvel. Inspired by the wind filled sails of an Arab trading ship, the sail facade fea-

tures a unique double-skinned Teflon-coated woven glass fibre screen.

• The Dow Corning product range was chosen to provide the reliable solutions such a unique

construction project required, especially under these particular weather conditions. The facade

was sealed with Dow Corning 993, Dow Corning 984 and Dow Corning Q3-3793 silicone seal-

ants. The very large aquarium in the foyer was sealed with Dow Corning 795, while Firestop 400

was used internally. In fig. 4 Burj-Al-Arab is shown.

The Dow Corning product range was once again chosen to provide the reliable solutions such a

unique construction project required, especially under these particular weather conditions. The

facade was sealed with Dow Corning® 993, Dow Corning® 984 and Dow Corning® Q3-3793

silicone sealants. The very large aquarium in the foyer was sealed with Dow Corning® 795.

Firestop 400 was used internally. Additionally, the completion of the project required Dow

Corning’s co-operation with companies in the UK, US, Japan and Dubai. Dow Corning success-

fully met the challenge of delivering solid solutions for imaginative construction projects when

operating on an global basis. Combining the latest technological trends and working globally,

Dow Corning has sealed what is considered as a symbol of Arabian hospitality. The Burj-Al-

Arab Hotel symbolises the very essence of Dubai, embracing the best of the new alongside tradi-

tions of the past [12].

Fig. 4: Burj-Al-Arab (source: http://ainkpisan.blogdetik.com/2009/08/19/17/burj-

al-arab/)

3. Taipei-101

Taipei-101 situated in Taipei, Taiwan having a total height of 508 metre used to be the tallest

building in the world before Burj Khalifa was constructed. It costs around ` 350 crores. Its con-

struction started in June, 1998 and finished in 2004. The reason behind its name is that it has 101

floors.

Skyscrapers must be flexible in strong winds yet remain rigid enough to prevent large sideways

movement (lateral drift). Flexibility prevents structural damage while resistance ensures comfort

for the occupants and protection of glass, curtain walls and other features. Most designs achieve

the necessary strength by enlarging critical structural elements such as bracing. The extraordin-

ary height of Taipei 101 combined with the demands of its environment called for additional in-

novations. The design achieves both strength and flexibility for the tower through the use of

high-performance steel construction. Thirty-six columns support Taipei 101, including eight

"mega-columns" packed with 10,000-psi concrete. Every eight floors, outrigger trusses connect

the columns in the building's core to those on the exterior.

These features combine with the solidity of its foundation to make Taipei 101 one of the most

stable buildings ever constructed. The foundation is reinforced by 380 piles driven 80 m into the

ground, extending as far as 30 m into the bedrock. Each pile is 1.5 m in diameter and can bear a

load of 1,000 metric tons - 1,320 metric tons. The stability of the design became evident during

construction when, on March 31, 2002, a 6.8-magnitude earthquake rocked Taipei. The tremor

was strong enough to topple two construction cranes from the 56th floor, then the highest. Five

people died in the accident, but an inspection showed no structural damage to the building, and

construction soon resumed. In fig. 5 Taipei 101 is shown.

The structural systems used in Taipei 101 draw a lot from other buildings in the Taipei region.

They can generally be classified into 2 types

a) Hysteretic Dampers

- Triangular Added stiffness and damping damper (TADAS)

- Reinforced ADAS damper (RADAS)

- Buckling Restrained Braces (BRB)

- Low Yield Steel Shear Panel (LYSSP)

Fig. 5: Taipei 101 (source: http://www.travelodestination.com/the-worlds-tallest-

skyscraper-taipei-101/)

b) Velocity Dampers

- Visco - Elastic dampers (VE)

- Viscous Dampers (VD)

- Viscous Damping Walls (VDW)

Currently, there have been more applications using viscous dampers than other velocity type

dampers. This may be due to the facts that the design procedure for implementing the viscous

damper is relatively simpler and the analytical model is available in the popular computational

tools such as SAP2000 and ETABS [13].

4. Dubai Infinity Tower

Dubai Infinity Tower, situated in Dubai, UAE is the first building on earth having twists of full

90 degrees from its base to its crown .It has a total height of 306.9 metres with total no. of 73

floors. It will contain studio, 1, 2, 3, and 4 bedroom apartments, along with 11 loft floors and 3

penthouse floors. Amenities at Infinity Tower include a landscaped podium, retail outlets, chil-

dren's nursery, gymnasium, outdoor swimming pools, built-in wardrobes, high-speed Internet,

and outdoor tennis court [14].

The architects proposed the twisting geometry of the Tower as a means to maximize the views at

different elevations. The Tower is founded upon a 3 meter thick reinforced concrete mat founda-

tion which is supported by ninety-nine 1.2 meter diameter bored, cast-in-place reinforced con-

crete piles extending approximately 30 meters below the mat foundation.

Fig. 6: Dubai Infinity Tower (source: http://gizmodo.com/356895/infinity-tower-to-twist-by-90-over-dubai-marina)

The lateral load resisting system for the Tower consists of a combination of a moment-resisting

perimeter tube frame and a circular central core wall, connected by the two-way spanning rein-

forced concrete flat plate slabs at each level acting as rigid diaphragms. This system maximizes

the effective structural ‘footprint’ of the Tower by utilizing a significant amount of the vertical

reinforced concrete for lateral load resistance.

The design philosophy for the Tower is based upon the exterior form of the building as a direct

expression of the structural framework. The engineers studied a series of options for the peri-

meter frame in order to create the unique twisting geometry of the Tower. Ultimately it was de-

termined that there were distinct advantages to stacking the columns. Each column slopes in one

direction, and is offset over the column below, in order to generate the twisting building form.

As the perimeter columns ascend from story to story, they lean in or out, in a direction perpen-

dicular to the slab edge. At every level, the columns shift in position along the spandrel beams so

that each column maintains a consistent position at each floor relative to the tower envelope. The

corner columns and the six (6) interior columns twist as they ascend.

Due to the unique twisting geometry of the Tower, the structure has a natural tendency to un-

dergo additional horizontal ‘twist’ movement under gravity loads, a significant portion of which

results from the self-weight of the cast-in-place structure. Additional movement is expected dur-

ing construction and over the life of the structure due to creep and shrinkage effects of the cast-

in-place concrete. In order to understand the potential movement of the structure, a detailed ana-

lysis was performed taking into account the anticipated construction sequence, and time depend-

ent variables; such as creep, shrinkage, and variation in concrete material properties [14].

Advantages of Modern Building Materials

The main advantage of modern building materials is that they are very strong and reliable in

comparison to the common and older building materials. For example, steel is more reliable as

well as strong than ordinary bamboo or such type of things. Moreover steel should not be re-

placed by the same after certain interval of time as in case of other materials like bamboo or

wood this should be done periodically; as it is affected by moisture etc. Moreover the traditional

building materials such as bamboo, wood etc. are enhancing deforestation while they modern

building materials are not.

Let’s take an example to see how modern building materials are far better than the ordinary com-

mon materials. It is known that ceiling in common houses is are made up of ply wood or other

wooden things .But when it comes to modern technology, it can be seen how other materials are

being used to replace ordinary wood etc.

Aluminium Ceiling

Aluminium ceilings are installed like all other drop ceilings as the panels are fitted to the previ-

ously built framework. Those ceilings are very endurable and look attractive even after long

time. As aluminium ceilings consist also from different panels it is not hard to install further

lights or ventilation to the ceiling. To build those aluminium ceilings an aluminium alloy has

been created to especially suit to manufacture those beautiful art metal ceiling panels. Alu-

minium is a corrosion resistant, very durable product that does not rust, unlike steel, which is

used by some manufactures of pressed tin. The ceiling panels are still widely known as pressed

tin even though they are not made from tin, but from long- lasting aluminium. When special alu-

minium alloy is pressed into different ceiling panels it holds its shape permanently and hardens

substantially. Aluminium ceiling is longer- lasting than a plaster ceiling. These ceilings will not

rust or crack and the material that they are made from are non- porous, therefore it resists mois-

ture and odour very well. Decorated aluminium ceiling panels add more value to your home than

it costs to have them installed or install them yourself. They can be painted in a lot of different

ways creating works of art on your ceiling to your flavour [15].

Steel Ceiling

A metal ceiling panel designed and patented at Soundproof Ceilings, the innovative Click panel

installs easily onto standard 15/16" suspension system for new construction areas or existing grid

for remodelling projects. Featuring a downward design which aids in the ease of installation and

allows future access to the area above the suspended ceiling. The Click panel is the answer for

the ceiling mechanic and building maintenance engineer. The unique spring action clips on each

panel allows the installer to hear an audible "CLICK" when the panel is properly positioned and

prevents the panel from being dislodged or moved. A specially designed removal tool provides

authorized personnel with easy access. Design and function harmonize with a host of beautiful

metallic and painted finishes, which can be customized to suit your specific design applications.

The Click is available with either 1/4" reveal edge detail or a flush bevelled edge for a com-

pletely concealed system. Steel or aluminium panels are available and can be used with standard

light fixtures and diffusers. Custom acoustical perforated panels are also available [16].

In the present, the main alternative material available is concrete block, which has several ad-

vantages stated as:

1. Fast in construction.

2. Give more spaces, whereas bearing wall can be constructed with 200mm thick.

3. A relatively low cost, since cement mortar used is much less than that required for stone.

Nowadays, building using concrete block in Yemen cost about ` 75 per square meter.

4. Have good and acceptable bearing strength make it applicable for constructing bearing wall

[17].

Disadvantages of Modern Building Materials

The major disadvantage of modern building materials is that, it is costlier than the old traditional

materials. Besides the natural building materials can be obtained without any cost. So, the mod-

ern building materials seem to be costlier than the other materials due to which people of devel-

oping countries cannot afford for modern building materials.

Another major disadvantage of modern building materials is associated with their repair and re-

placement, which is a difficult task as compared to the repair and replacement of old traditional

materials.

Modern building is fire-proof, but it is not noise-proof. In fact, measurements have shown that it

is a good deal noisier than were our traditional designs, where there was a discontinuity of struc -

ture, and massive, but poorly conducting, materials. Steel-framed and Ferro-concrete building,

cement mortar and plaster, to say nothing of a general ramification of central heating, running

water and other piping, have replaced the softer brickwork, lime mortar and plaster, wooden

beams, joists and studding, and the localised piping of the older houses.

Disadvantages of constructing using concrete block can be stated as

(1) Have poor thermal isolation.

(2) Building using concrete block required a relatively regular shape of wall [17].

Conclusions

From the above case studies, we can conclude that the modern building material is raison d’être

for the modern buildings. The scientific method implemented in the construction is proving a

boon and bliss to development as besides making living easy and comfortable, it also guarantees

safety to a certain degree. The techniques such as Fire proofing, Earthquake proofing enhances

the longevity of the building in addition to its withstanding the calamity. The chosen four case

studies Burj Khalifa, Burj-Al-Arab, Taipei 101 and Dubai Infinity Tower is nothing but the

product of man’s scientific thoughts down the ages and its implementation through the use of

sophisticated instrumentation, engineering and modern building materials. Most importantly, it

is a great feat in the history of modern engineering since the application of the advancement of

technology through engineering is making it possible to bring them to reality. Undoubtedly there

are shortcomings in certain case but the overall impact of all the effects has to be taken into con -

sideration.

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