superstructure, substructure and costing
TRANSCRIPT
17
CHAPTER 3
SUPERSTRUCTURE DESIGN
3.1. Structural Design Methodology and Audit
Superstructure design was carried out systematically in two stages - preliminary and
detailed design, in order to produce the optimum design for the client. Finite Element
Analysis (FEA) was employed for most of the structural design and analysis,
especially through ETABS and SAFE. Lastly, the manual design calculations were
developed for cross-checking and design audit purpose. The flow chart below
illustrates the structural design methodology that has been adopted for the entire
design process. The design methodology is summarised in Figure 3.1 bellow.
Figure 3.1: Structural design methodology and audit
3.2. Codes and Standard for Detailed Design
Below are the code and standards used for the superstructure detailed design, British
Standard are the main references especially for RC and Steel design.
18
Concrete design BS 8110:1997
Steelwork design BS 5950: Part 1
Weight of materials BS 648
Imposed loads BS 6399: Part 1
Section shapes BS 4848: Part 4
UBBL 1984: 2010
Foundations BS 8004 (1986)
Site investigation BS 5930 (1999)
3.3. Preliminary Design (Finite Element) Using ETABS
Integrated Building Design Software (ETABS) is a Finite Element software
produced by Computer and Structure Incorporation (CSI) to analyze the building
performance and structural design of vertical elements such as columns, walls and
foundation system based on Finite Element Method. The initial sizing of vertical
members was obtained by manipulating the concrete grades, member size,
reinforcement bars, location of support and etc.
After obtaining the preliminary sizing of vertical elements, the detailed design of RC
flat slabs was carried out in SAFE - Structural and Earthquake Engineering Software.
SAFE is widely used for modeling of RC flat slab, analysis, designs & preliminary
sizing based on Finite Element Method
3.4. Detailed Design of Slab System
Functions: Modelling of reinforced concrete flat slabs and beams, analysis, designs
and preliminary sizing using finite element method.
3.4.1 Design procedure of flat slab system using SAFE (e.g. Level 7)
Step 1: Tracing of structural elements from architectural drawings
19
Figure 3.2: Architectural drawing (Level7) Figure 3.3: Tracing of structural
elements
Step 2: Import scaled drawing into SAFE
Figure 3.4: Scaled drawing - Imported into SAFE
Step 3: Define and assign materials properties
Structural Properties
Slab Properties
Beam Properties
Column Properties
=
=
=
S275
No beam
C300
(Thickness 275mm)
(Flat slab system)
(Rectangular column 300mm x 300mm)
20
Wall Supports = W200 (RC walls thickness 200mm)
General Properties
Modulus of Elasticity = 27 kN/mm²
Poisson Ratio = 0.2
RC Unit Weight = 24 kN/m³
Concrete Cover = 40 mm
Concrete Strength = 35 N/mm²
Reinforcing Yield Stress = 460 N/mm²
Step 4: Define loading schedule
Dead Load = Self weight of slab
(24 kN/m³)
Live Load
=
=
2.0 kN/m²
0.75 kN/m²
(BS 6399: Part 1 - Normal functions)
(Roof - Maintenance purpose)
Superimposed = 1.0 kN/m² (Brick wall partitions + screed /
Dead Load (SDL) finishes)
Special Case (SDL) = 26.0 ~ 28.0 kN/m² (Roof water tank)
= 5.0 kN/m² (Roof Garden - Assume 50cm thick
soils)
= 7.5 kN/m² (M&E - Assumptions w/o specifications)
Step 5: Define analysis options
Load Combination = SLS (serviceability loads) - Checking of deflection
DL x 1, LL x 1, SDL x 1
= ULT (Ultimate loads) - Structural Design Purpose
DL x 1.4, LL x 1.6, SDL x 1.4
Static Load Case
Step 6: Assign structural elements, imposed & transferred loads
21
Figure 3.5: An example of flat slab model in SAFE (Level 7)
Step 7: Checking of slab deflection
After running the finite-element analysis, the slab deflection is checked under two
different conditions - elastic uncracked deflection and long term crack deflection.
As displayed in the deflection contour diagram (Figure 26), the slab deflection under
long term crack condition is more critical than the elastic-uncracked condition, due to
the effect of creep and shrinkage. Therefore, for design purpose, the long-term
deflection was checked in accordance to the BS code, which specified that the
maximum slab deflection between two unsupported span should not more than
L/250 or maximum 40mm, whichever is smaller. In case of excessive deflection,
several factors were manipulated including concrete grade, slab thickness, vertical
support and so on, until it fulfils the requirements.
Figure 3.6: Slab deflection under serviceability loads
22
Figure 3.7: Slab deflection under serviceability loads
Following on the procedures explained above, the analysis and design was carried
out for the whole building (top roof to ground floor):
3.4.1. Design Summary
3.4.2. Special Design Considerations
Case 1: Top Roof
Due to the critical loads imposed by the roof water tank, the slab deflection was
critical even though the slab thickness has been increased to 300mm, with concrete
grade 50. So instead of keep on increasing the slab thickness, RC beams were
introduced for a more economic design, and in the end the deflection was kept within
the limit as shown below:
23
Figure 3.8: Introduction of RC beams
Case 2: Level 3 and Level 4
Figure 3.9: Variation of slab thickness due to different functions and loads
Case 3: Level 2
At level 2, critical deflection occurred at the 13m span car porch supported by the
columns alone at the slab edge, so we introduced steel beams to resolve the issues in
order to look after the aesthetic value. RC beams are not practical in this case as it
will be very deep in size and indirectly reduce the clearance height for the car porch.
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Figure 3.10: Critical deflection at 13-m span car porch
Figure 3.11: Deflection controlled through steel beam support
Case 4: Level 1
Due to the structural requirements, additional columns are proposed at the ground
floor lobby area to cater for excessive deflection.
Figure 3.12: Location of proposed additional columns at the ground floor
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3.4.3. Slab Reinforcement
For the slab reinforcement bars, the minimum reinforcement as specified in the BS
8110 is 0.13% of the total cross-sectional area. To facilitate our calculation, the slab
was designed based on the per meter strip, we provided T12 @ 200 for the basic
rebar, top and bottom in X and Y direction, in order to fulfill the requirements.
Consider per meter strip:
BS 8110 = Minimum Reinforcement 0.13% bh
= 0.13 % x 1000mm x 300 mm (max. slab thickness)
= 390.0 mm²
Provide T12 @ 200 for basic rebar = 565.0 mm²
Figure 3.13: Typical drawing of slab basic rebar
On top of the basic rebar, additional reinforcements are required at certain area
where the bending moment and shear force are critical. To come out with a more
accurate and economic design, SAFE was used to generate the amount and location
of additional rebars on top of the basic rebar, based on per meter strip. The diagram
below illustrates an example of additional top rebar near to the column support at
level 7 slab, where higher number of compression bars are required due to the critical
flexural stress at the slab.
Thus, for one piece of continuous RC slab, the additional rebars will span in X and Y
direction, top and bottom of the slab. The final output of the design will be basic
rebars spanning each-way and each-face of the slab, plus the additional rebars at
certain area where there are excessive bending moment and shear force. The diagram
below illustrates the detailed drawing of additional top reinforcement bars in addition
to the basic rebars at level 7.
26
3.4.4. Risk Assessment & Special Design Considerations
Risk assessment 1: Punching shear failure
Reference: Behavior of Reinforced Concrete Flat Slab, P.E. Regan, CIRIA
Report 1989
Punching Shear
1) Most critical consideration in flat plate design around the columns
2) Punching at a single column causes a major redistribution of load effects, and
lead to potential progressive collapse
3) Instead of using thicker section, shear reinforcement in the form of shear
heads, shear studs or stirrup cages may be embedded in the slab to enhance
shear capacity at the edges of walls and columns
4) Drop panel is utilized to thicken the slab locally to eliminate punching shear
failure
5) All critical columns at the building were checked against the punching shear
failure, the top roof columns are exposed to punching shear
6) Based on the design calculation (Appendix C) the slab thickness was increased
locally by providing the drop panel and shear studs to eliminate this issue.
Risk assessment 2: Holes Adjacent to columns - Trimmer Bars for Slab Openings
Reference: Design of Reinforced Concrete Flat Slabs to BS 8110, Report 110
(2nd Edition) - R T Whittle MA Ceng MICE
“In the flat system, holes should not be placed at the column face, as they
considerably reduce the moment transfer in one or both directions. Even if torsion
links are provided in the slab adjacent to the column, it does not develop its design
couple until large rotations occur”
27
Figure 3.14: Holes adjacent to columns in flat slab system
When it is necessary to cut bars to fit a hole, replacement bars of the same diameter
should be positioned along all sides of the hole. All replacement bars should extend a
tension anchorage length beyond the edges of the hole.
Risk assessment 3: Concrete Cover - Fire Rating
Architect’s recommendations:
-1 hour fire rating
-BS 8110 Part 1, Clause 3.3.6 - corresponding to minimal cover of 20 mm for
continuous slab
Our recommendations:
-25mm (20+5) for all slabs and columns except:
-For all concrete faces in contact with water or soil = Cover 40mm
(Applicable to ground floor slab & top roof slab)
3.4.5. Manual Design Calculation for Flat Slab Design
Refer to the folder name superstructure design in the attached CD.
3.5. Detailed Design of Column System
3.5.1. Column Reactions based on the SAFE Output - Finite Element Method
The ultimate column reactions were obtained from the SAFE output (Figure 45) as it
is more accurate and precise compared to the approximate area method. The
cumulative loadings for all floors are enclosed in Refer to the folder name
superstructure design in the attached CD.
28
Figure 3.15: Column reactions generated from SAFE
To carry out the design, we have developed our own spreadsheet (attached in the
CD) and design calculations (attached in the CD). The design summary is shown in
the table below:
Table 3.1: Design summary for RC columns
The RC columns were designed for the whole building based on the most critical
ultimate loads obtained for each floor. The smallest column size is 300 x 300 for the
top roof and increased gradually to 525 x 525mm at the ground floor, all using
concrete grade 35.
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We have tried to manipulate the concrete grade but apparently it did not helped much
in reducing the column size, therefore we decided to use the same concrete grade for
all level to minimize variations and facilitate the construction on site as well.
Basically there were no any changes to the proposed column location in the
architectural drawings, but additional columns are required to be introduced at
ground floor to cater for slab deflection.
As explained, the column dimension can be standardized for the whole floor to
minimize variations and facilitate the contractor’s works, but it is not cost efficient as
the column size was designed based on the most critical load. Therefore, we carried
out some value engineering by designing the column size in batches based on the
loading range, and 5 typical column sizes were produced for the whole building.
Based on our study, the proposed method will produce some minor variation in the
column size for a particular floor (Figure 48), and the same process was repeated for
the whole building (Table 5). The tabulated results shown that the second method
will save the concrete volume by approximately 50%.
Table 3.2: Design of columns by batches based on the loading range
3.5.2. Detailing of RC Columns
The detailing of the RC columns was carried out strictly in accordance to BS 8110,
especially the main bars, links and hooks.
Detailing of RC Columns - In Accordance to BS Code of Practice:
Main Bars:
Minimum Reinforcement = 0.4% of Cross-Section
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Maximum Reinforcement
Maximum Reinforcement
=
=
6.0% of Cross-Section (Vertical Cast)
8.0% of Cross-Section (Precast)
Minimum Bar Size
Minimum No. of. Bar
=
=
T12 or T13
4 for Square Column
= 6 for Circular Column
Links:
Link Spacing
=
12 times the diameter of the smallest main bar
compression bar (Maximum 300mm)
Link Size = Not less than 1/4 of the largest compression bar
Hooks:
To be provided if face bar is more than 150mm of restrained bar
The detailed drawing for second method, where the column sizes were designed
based on the loading range is shown in Figure.
Figure 3.16: Detailed drawing of column design (method 2)
The typical detailing of RC column in cross-sectional view, especially the anchorage
length and compression lap is shown in Figure 51. Hooks are provided when the
spacing of the face bar is more than 150mm of restrained bar.
3.5.3. Risk Assessment & Special Design Considerations
Risk assessment 1: Connection between Columns and Flat Slabs - Lateral Stiffness
Reference: Design of Reinforced Concrete Flat Slabs to BS 8110, Report 110
(2nd Edition) - R T Whittle MA Ceng MICE
“The connection between the columns and flat slabs is unsuited to resist large
bending moments. Even if the moment capacity is sufficient, the maximum shear
capacity is likely to be exceeded because of the effect of moment transfer. Thus,
31
whenever possible, horizontal loading should be resisted by shear or core walls
making the structure a 'no-sway' frame.”
1) Edge columns have limited moment transfer capacity
2) Internal columns resist most of the moment, but this reduce the shear capacity of
the adjacent slab
3) Holes in the slab close to a column and in the plane of bending drastically reduce
the moment transfer capacity.
Due to this reason, the lift core was proposed to be converted as a shear wall (Figure
52 - yellow boxes). Initially the staircase RC walls were suggested to be replaced
with shear walls in order to obtain more uniform distribution of lateral stiffness, but
apparently the idea was not feasible as there are windows at the staircase that might
interrupt the structures.
Figure 3.17: Proposed shear wall locations
Reference: BS 6399 Part 2: Code of practice for wind loads
Notional horizontal load
“All buildings should be capable of resisting a notional design ultimate horizontal
load applied at each floor or roof level simultaneously equal to 1.5 % of the
characteristic dead weight of the structure between mid-height of the storey below
and either mid-height of the storey above or the roof surface [i.e. the design ultimate
wind load should not be taken as less than this value when considering load
combinations 2 or 3.”
32
According to BS 6399, it is mentioned that all buildings should be capable of
resisting a notional design ultimate horizontal load which is equivalent to 1.5 % of
the characteristic dead weight.
This is not a compulsory requirement for building less than 10 storeys, but we carried
out the analysis by using ETABS to analyze the lateral deflection based on 1.5 % of
the building dead loads (Figure 53). The deflection diagram shows that the lateral
drift is approximately 46mm, which is below the lateral deflection limit as specified
in the code (Figure 55).
Figure 3.18: Checking of lateral deflection through ETABS (Finite Element Method)
Figure 3.19: Lateral deflection of the building
33
Figure 3.20: Lateral deflection diagram of the building
Risk assessment 2: Precautions Against Progressive Collapse - Bottom
Reinforcement at Joints
Reference: Behavior of Reinforced Concrete Flat Slab, P.E. Regan, CIRIA
Report 1989
“As a precaution against progressive collapse occurring as a result of a punching
failure at a slab/column joint, and the consequent increases of shear and unbalanced
moments at neighboring joints, some bottom reinforcement should be provided at
all joints. It is suggested that the amount of reinforcement be determined by the
condition that:”
In order to mitigate the risk against progressive collapse, we have provided bottom
reinforcement at all joints, especially the connection between RC slab and column.
As shown in the drawing, the bottom reinforcement bars should span in both X and
Y directions:
34
Figure 3.21: Typical RC slab & column connection details
Risk assessment 3: Safeguarding of Vertical Elements Against Vehicular
Impact
Reference: BS 8110
Safeguarding against vehicular impact
“Where vertical elements are particularly at risk from vehicle impact, consideration
should be given to the provision of additional protection, such as bollards, earth
banks or other devices”
The RC columns at the car porch are exposed to the risks of vehicular impact, which
might lead to the collapse of the slab, therefore addition protection such as structural
column protectors should be provided (Figure 57).
35
3.6. Detailed Design of Beams System
3.6.1. Introduction of Minimal Beams at the Building
For the beams design, there are a very minimal number of beams at the top roof and
level two car porch due to the flat slab system (Figure 58). Based on the beam
moment and shear diagram generated by SAFE (Figure 59 and 60), the designs and
detailing were carried out in accordance to BS 8110.
Figure 3.22: Location of RC Beams
General Design Considerations and Detailing - RC Beams:
Based on BS 8110 Simplified Rules:
1) Minimum areas of shear reinforcement in beam - Table in BS code of
practice
2) Minimum areas of compression reinforcement for rectangular beam = 0.2%
total areas of concrete
3) Minimum areas of tension reinforcement for rectangular beam = 0.13% total
areas of concrete
4) Maximum tension/compression reinforcement = 4% gross cross-section
concrete
5) Minimum bar size = T12
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6) Beams whose depth 750mm or more should be provided with side lacers
maximum 250mm spacing
7) Maximum amount of reinforcement in a layer including tension laps. At laps,
the total diameter of all reinforcement provided in a particular layer should
not exceed 40% the breadth of the section at the level.
3.6.2. Manual Design Calculations
Design of RC Beams based on:
Refer to the attached CD.
3.6.3. Design summary
Based on the design, the final beam sizes were determined to be 200 x 500mm RC
rectangular beams, while steel beams were employed at level 2 car porches, as shown
below. The diagram below shows the detailed drawing of RC beams and steel beam,
including the reinforcement for tension and compression bars.
Figure 3.23: Detailed drawing of beams design
The typical details for RC beams connection to the columns are illustrated below,
which shows the anchorage length.
3.6.4. Risk Assessment and Special Design Considerations
Risk assessment 1: Corrosion Resistance
The risks associated with RC column-to-steel beam connection mainly come from
the seismic loading, which is not applicable in our design. However, the steel beams
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supporting the car porch are exposed to weather conditions; therefore it should be
protected by a coating, for example galvanized.
3.7. Other Design Considerations
3.7.1. Design of Parapet Wall for Roof
Figure 3.24: Typical design of parapet wall
Risk assessment: Moisture penetration problems
The top of a parapet wall is vulnerable to moisture penetration problems. Choosing
an appropriate cap is an effective way to eliminate this condition. A variety of
materials are available to cap off the wall, with limestone, terra cotta, hard-fired clay,
or precast concrete preferred. These materials have thermal properties similar to
those of brick and concrete masonry.
3.7.2. Design of Plinth Details
A plinth is the base or platform upon which a column, pedestal, statue, monument or
structure rests, it also refer to the mass topping of concrete blinding.
38
Figure 3.25: Typical design of plinth
3.7.3. Design of Lintel Details
A lintel is defined as a structural horizontal block that spans the space or opening
between two vertical supports. Typically above openings, a lintel is used, not a bond
beam.
Figure 3.26: Plinth lintels details
Risk assessment: Construction stability
Where concrete floors are to be placed onto lintel, the lintels should be supported
temporarily until the floors have been completed to reduce the risk of shock loading
or uneven loading of the lintels.
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3.7.4. Staircase Design
Figure 3.27: Staircase design
3.7.5. Lift Motor Room Hosting Beam Details
Figure 3.28: Typical lift motor room hosting beam details
3.7.6. Lift Core Wall
Figure 3.29: Typical design of lift core wall
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CHAPTER 4
SUBSTRUCTURE DESIGN
4.1. Soil Investigation
The design of a structure which is economical and safe to construct, is durable and
has low maintenance costs, depends upon an adequate understanding of the nature of
the ground. This understanding comes from an appreciation of the distribution of the
materials in the ground, and their properties and behaviour under various influences
and constraints during the construction and lifetime of the structure. An adequate
and properly structured soil investigation is therefore an essential part of any civil
engineering or building project (Association of Geotechnical and Geoenvironmental
Specialists, 2004).
4.1.1. Soil Investigation Layout
Total number of bore holes proposed = 5
Mackintosh probe = 13
Estimated cost = (RM 3447 x 5) + (RM139 x 13) + (RM794 x 13) = RM 19, 836
The soil investigation layout is represented in Figure 4.1 bellow.
Figure 4.1: Soil investigation layout.
41
4.1.2. Soil Strata of Proposed Site in General
Based on the soil investigation report, the following is the data represented in Figure
4.2 of the soil strata:
Thickness, m Strata Description
Soil
Den
sity
: St
and
ard
Pe
netr
atio
n T
est
Depth, m SPT, N
2.40
Clay with sand
Very soft soil
1.5
3
4.5
6
7.5
9
10.5
12
13.5
15
16.5
18
18.6
20
21.6
24
28
2
7
1
0
7
0
4
1
7
9
14
16
28
40
50
50
50
5.50
Sand with gravel
Loose soil
8.60
Silt with sand
Very soft soil
13.00
Clay with silt
Loose soil Ground water table is found here.
17.40
Sand with gravel
Loose to medium dense soil
18.60
Sand with clay
Medium dense soil
21.50
Bed rock
Strong soil
Figure 4.2: Soil strata of proposed site
4.1.3. Risk Assessment of Underneath Soil
In determining the classification of the soil type, in this case, where the site has a
layered geological stratum, the soil has to be classified according to the weakest soil
type. The soil types classified here to be considered in design parameters are dark,
dense, sandy and clayey. The permeability of soil is derived from the weight
42
percentage of fine fraction (fraction of particles smaller than 0.06 mm) in the soil
sample (Neznal, 1995). The main disadvantage of the method is given by the fact
that other factors influencing the permeability (soil moisture, density, porosity) are
not taken into consideration. Furthermore, the analysis of one soil sample cannot
describe a heterogeneous geological environment (Neznal, 1995).
Table 4.1: Permeability and moisture content of soil types (Davis & Wilson, 2010)
Soil Texture Permeability Moisture Content Sand high low Silt low high
Clay low high
The sandy layers of the soil are regarded to be non-cohesive. They have lower
density and more poorly graded resulting in loosely packed, low inter-granular
friction and low friction angle. There is also high liquefaction potential that may
causes loss of strength controlled by a combination of low density, degree of
saturation and poor gradation. The higher permeability of sandy soil is undesirable
for water containment structure. The clayey soil underneath are soft and finer. It is
over cohesive with presence of water. There is a high risk of settlement for building,
thus precautions have to be taken into account in designing the foundation type.
However, the softness of the soil makes it easy for jack-in pile penetration for
foundation. This layer also has a low unconfined compressive strength, making the
use of jack-in piles further compressing the soft clay towards unbearable capacity.
4.2. Foundation
4.2.1. Type of Foundation
Type of foundation used for the project is deep foundation. The site contains very
soft clay, very soft silt and loose sand at depth 0 to 16m. In addition, ground water
table found at depth of 13m and bedrock layer found at depth of 19m. The loadings
from structures will rest on bedrock (SPT=50) with 4m as socket piles.
Type of deep foundation used is precast spun pile. Spun piles are chosen compare
with precast square RC piles because of these reasons:
a. Better bending resistance
b. Higher axial capacity
c. Better manufacturing quality
43
d. Able to sustain higher driving stresses
e. Higher tensile capacity
f. Easier to check integrity of piles.
g. Similar cost to RC square piles.
The spun pile will use cross fin shoe for easy penetration to bedrock layer and
reduces slipping failure when reaching the bedrock layer. Since the site near high end
residential areas, method of pile installation used is hydraulics jack-in.
Jacking force to penetrate the spun piles is 3800kN. Hydraulics jack-in produce
lower noise, vibration and pollution compare with hammer method and bored
method. It is also average in cost for both methods. Hydraulics jack-in can achieve 6
piles installation per day which is high productivity compare with common used
bored piles.
4.2.2. Design of Foundation
Pile section used for chosen spun pile is 500mm diameter with Fcu equivalent with
45N/mm² and 10T9 reinforcement. Bearing capacity from the soil will act on surface
area per length of piles and base of piles. Calculations of soil bearing capacity as
follow:
For Skin Friction, Fs
Fs = k x SPT Where k = 2N/mm²
Skin Resistance, Qs
Qs = Fs x As
Where As is the pile surface area
For Base Resistance;
Using Meyerhof method
Base friction, Fb
Fb = (40NSPT) Lb /B < 400NSPT Where NSPT is the average uncorrected blows count within 10B above and the 4B
below the pile base.
Lb is the depth of penetration of pile tip into the bedrock layer.
Ultimate Base Resistance, Qb
Qb = Fb x Ab
Where Ab is area of pile's base Allowable Pile Load, Qall
Qall = (Qs + Qb) / FS
Where Factor of Safety, FS = 2.5 Structural Capacity of Pile, Qst
Qst = 0.25 fcu x A
44
Detail calculations for soil bearing capacity as in Appendix 3.1: Soil bearing capacity
in the folder named Substructure design on the attached CD.
4.2.3. Piling Layout
Summary of piles groups as shown in table 4.1 below:
Table 4.2: piles groups
Piles Group Quantity Piles Group Quantity Piles Group Quantity
1 Pile 48 3 Piles 10 5 Piles 4
2 Piles 29 4 Piles 12 6 Piles 7
Number of piles per column = Unfactored load at column
Allowable pile load
Where allowable pile load calculated = 1163kN
Calculation of piles per column as in Appendix 3.2: Number of piles per columns in
the folder named Substructure design on the attached CD.
Piling layout for spun pile foundation as Figure 4.3 below:
Figure 4.3: Piling layout
45
Spun pile details
Figure 4.4: Spun pile detailing
Figure 4.5: Cross pin pile shoe detailing
4.2.4. Risk Assessment of Foundation
Pile tilt and move in soft ground
Pile installation using hydraulics jack-in should reduce the risk of pile tilt while
driven into the soil compare with hammer installation method. Verticality of piles
should be checked before and after applying jacking forces. This method also prevent
pile heave due to pressure relief.
Irregular bedrock profile
Irregular bedrock layer profiles will cause piles slip when hitting hard layer. Using
cross pin pile shoes as recommended should encounter such risk.
46
Integrity of piles
Integrity on piles group should be checked in pile group efficiently calculations. It is
also will be checked by piles load test after installation on piles in group.
Settlement of piles
Settlement of piles will occur due to negative skin friction from soil. Piles will allow
to settle and settlement after applying load test should be monitor.
Failure due to installation
Handling of piles from transportation to installation of piles should be checked by
site engineer. Selection of pile installation contractor having more experience should
be considered.
4.3. Piles Cap
4.3.1. Design of Piles Cap
Refer to Figure 4.4 for illustration.
Mx, My = Moment about axis x and y
2l at least 2D of pile
t at least 150mm
Max pile load = TL / 4 + My/2l + Mx/2l
Min pile load = TL / 4 - My/2l - Mx/2l
Total axial load (TL) = P + Wpilecap
Where; P = Axial load in column
Wpilecap = Self weight of pile cap
Figure 4.6: Typical pile cap
47
Longitudinal reinforcement (using bending method);
Moment at face of the column, Mf
Mf = 2 x Max pile load (l - c₂/2)
Area of reinforcement, As As = Mf / 0.95fyz
Beam shear:
Shear at critical section, V
V = 2 x Max pile load
Stress at critical section, v
v = V/Bd < 0.8 √fcu
Enhanced resistance = 2dvc/av
Where vc = Design concrete sheer stress (Table 3.8:BS8110) and av = l/2
Punching;
Stress at column perimeter = P / (2d)(c1+c2) < 0.8 √fcu
Stress at critical perimeter = P / (4d)(2l-B) < 0.8 √fcu
Detail design of all pile cap types are in Appendix 3.3: Pile cap calculation in the
folder named Substructure design on the attached CD.
4.3.2. Pile Cap Details
Figure 4.7: Single pile cap detailing
48
Figure 4.8: Double piles cap detailing
Figure 4.9: Three piles cap detailing
Figure 4.10: Four piles cap detailing
49
Figure 4.11: Five piles cap detailing
Figure 4.12: Six piles cap detailing
4.3.3. Assessment of Pile Cap
Shear failure and punching failure in pile cap
Shear and punching failure should be checked and provide sufficient reinforcement
bars.
Eccentric loads from axial column
Columns should be checked for verticality during construction. A very small angle
change in verticality at level 1 columns will have greater affect to top most columns.
Pressure from soil to bottom of pile cap
Formwork installation for pile cap should have 50mm clearance from soil surface.
Installation of polystyrene should be considered as gap between soil and formwork.
50
4.4. Ground Slabs
4.4.1. Typical design for ground slabs
Design using Horizontal Structural Elements (RC Slab SAFE Modeling), slab
properties as follows:
Slab Properties: 275mm thickness
Beam Properties: Non
Wall Supports: RC walls thickness 200mm
General Properties;
Modulus of elasticity: 27 kN/mm² Poisson ratio: 0.2
RC Unit weight: 24 kN/m³ Concrete cover: 40 mm
Concrete strength: 35 N/mm²
Reinforcing yield stress: 460 N/mm²
Loading Schedule:
Dead load: 24 kN/m³ (Self weight of RC slabs, columns and beams)
Live load: 3.0 kN/m² (BS 6399: Part 1 - Normal functions)
Superimposed dead load (SDL): 1.0 kN/m² (Brick wall partitions + screed/finishes)
Special case load (SDL): 30 kN/m² (TNB substation and ground tank) and 7.5 kN/m² (M&E - Assumptions w/o specifications)
Slab Reinforcement Bars:
Consider per meter strip using BS 8110;
Minimum Reinforcement 0.13% bh
= 0.13 % x 1000mm x 300 mm (max. slab thickness)
= 390.0 mm²
Provide T12 @ 200 for basic rebar = 565.0 mm²
51
CHAPTER 5
MATERIALS QUANTITIES AND ECONOMICS
5.1. Concrete Price and Calculations
Based on the report produced by Construction Industry Development Board (January
and February Edition), the rates and prices of materials are obtained. The price of
concrete for slab, beam and columns are shown in Tables 5.1 below. For more details
refer to the folder name Materials quantities and economics in the attached CD.
Table 5.1: Rate of ready mix concrete
5.1.1. Calculation for Slab’s Concrete Costing
Calculation for slab costing is summarised in Table 5.2 bellow.
Table 5.2: Calculation for slab’s concrete costing
52
5.1.2. Calculation for Beam’s Concrete Costing
Calculation for beam costing is summarised in Table 5.3 bellow.
Table 5.3: Calculation for beam’s concrete costing
5.1.3. Calculation for Column’sConcrete Costing
Calculation for column costing is summarised in Table 5.4 bellow.
Table 5.4: Calculation for column’s concrete costing
53
Table 5.4: Calculation for column’s concrete costing (continued)
5.1.4. Calculation for Reinforced Concrete Staircases’sConcrete Coasting
Calculation for staircases costing is summarised in Table 5.5 bellow.
Table 5.5: Calculation for staircases’ concrete costing
5.1.5. Calculation for Reinforced Concrete Sheer Wall’sConcrete Coasting
Calculation for sheer wall costing is summarised in Table 5.6 bellow.
Table 5.6: Calculation for sheer wall’s concrete costing
54
5.2. Steel Price and Calculations
The calculation for the price of steel for slab, beam and columns are shown in the
tables below.
5.2.1. Calculation for RC Slab’sSteel Coasting
Calculation for RC slab’s steel costing is summarised in Table 5.7 bellow.
Table 5.7: Calculation for RC slab’s steel costing
5.2.2. Calculation for Reinforced Concrete Beam’sSteel Coasting
Calculation for reinforced concrete beam’s steel costing is summarised in Table 5.8
bellow.
Table 5.8: Calculation for reinforced concrete beam’s steel costing
5.2.3. Calculation for Universal Beam Coasting
Calculation for universal beam coasting is summarised in Table 5.9 bellow.
55
Table 5.9: Calculation for Universal Beam Coasting
Level
Number
of Beam
Beam Size
Cross Sectional
Area
(m2)
Average Beam
Length
(m)
Rate
(RM/m)
Price of UB
2
3
533 x 210 x 101 UB
0.0129
11.4
353.68
RM12,095.86
5.2.4. Calculation for RC Column’sSteel Coasting (Main Rebar)
Calculation for RC column’s steel coasting is summarised in Table 5.10 bellow.
Table 5.10: Calculation for RC column’s steel coasting (Main rebar)
Level
Column height
(m)
Column size
Num. of Column
Main Rebar
Length of rebar
(m)
Rate
(RM/m)
Price of Main Rebar
Top Roof
3
250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
47 6 0 0 0
4T32
12T25 12T32 16T32 32T32
564 216
0 0 0
14.91 9.10
14.91 14.91 14.91
RM8,409.24 RM1,965.60
RM0.00 RM0.00 RM0.00
8 4 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
37 16 0 0 0
4T32 12T25 12T32 16T32 32T32
592 768
0 0 0
14.91 9.10
14.91 14.91 14.91
RM8,826.72 RM6,988.80
RM0.00 RM0.00 RM0.00
7 4 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
29 23 1 0 0
4T32 12T25 12T32 16T32 32T32
464 1104
48 0 0
14.91 9.10
14.91 14.91 14.91
RM6,918.24 RM10,046.40
RM715.68 RM0.00 RM0.00
6 4 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
26 23 4 0 0
4T32 12T25 12T32 16T32 32T32
416 1104 192
0 0
14.91 9.10
14.91 14.91 14.91
RM6,202.56 RM10,046.40 RM2,862.72
RM0.00 RM0.00
5 4 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
22 17 15 0 0
4T32 12T25 12T32 16T32 32T32
352 816 720
0 0
14.91 9.10
14.91 14.91 14.91
RM5,248.32 RM7,425.60
RM10,735.20 RM0.00 RM0.00
4 4 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
30 22 18 1 0
4T32 12T25 12T32 16T32 32T32
480 1056 864 64 0
14.91 9.10
14.91 14.91 14.91
RM7,156.80 RM9,609.60
RM12,882.24 RM954.24
RM0.00 3 4 250 x 250
325 x 325 400 x 400 500 x 500 550 x 550
29 32 16 4 0
4T32 12T25 12T32 16T32 32T32
464 1536 768 256
0
14.91 9.10
14.91 14.91 14.91
RM6,918.24 RM13,977.60 RM11,450.88 RM3,816.96
RM0.00
56
Level
Column height
(m)
Column size
Num. of Column
Main Rebar
Length of rebar
(m)
Rate
(RM/m)
Price of Main Rebar
2 4.2 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
44 34 12 11 1
4T32 12T25 12T32 16T32 32T32
739.2 1713.6 604.8 739.2 134.4
14.91 9.10
14.91 14.91 14.91
RM11,021.47 RM15,593.76 RM9,017.57
RM11,021.47 RM2,003.90
1 5.2 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
36 33 16 13 4
4T32 12T25 12T32 16T32 32T32
748.8 2059.2 998.4
1081.6 665.6
14.91 9.10
14.91 14.91 14.91
RM11,164.61 RM18,738.72 RM14,886.14 RM16,126.66 RM9,924.10
Total 36.4 622 RM272,656.44
5.2.5. Calculation for RC Column’sSteel Coasting (Links)
Calculation for RC column’s steel coasting is summarised in Table 5.11 bellow.
Table 5.11: Calculation for RC column’s steel coasting (Links)
Level
Column
height (meter)
Column size
Num. of Column
Links
Length
of links (meter)
Rate
(RM/m)
Price of Links
Top Roof
3 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
47 6 0 0 0
R10-300 R10-300 R10-300 R10-300 R10-300
351.56 64.68
0 0 0
1.60 1.60 1.60 1.60 1.60
RM562.50 RM103.49
RM0.00 RM0.00 RM0.00
8 4 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
37 16 0 0 0
R10-300 R10-300 R10-300 R10-300 R10-300
377.4 235.2
0 0 0
1.60 1.60 1.60 1.60 1.60
RM603.84 RM376.32
RM0.00 RM0.00 RM0.00
7 4 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
29 23 1 0 0
R10-300 R10-300 R10-300 R10-300 R10-300
295.8 338.1 19.2
0 0
1.60 1.60 1.60 1.60 1.60
RM473.28 RM540.96 RM30.72 RM0.00 RM0.00
6 4 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
26 23 4 0 0
R10-300 R10-300 R10-300 R10-300 R10-300
265.2 338.1 76.8
0 0
1.60 1.60 1.60 1.60 1.60
RM424.32 RM540.96 RM122.88
RM0.00 RM0.00
5 4 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
22 17 15 0 0
R10-300 R10-300 R10-300 R10-300 R10-300
224.4 249.9 288
0 0
1.60 1.60 1.60 1.60 1.60
RM359.04 RM399.84 RM460.80
RM0.00 RM0.00
4 4 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
30 22 18 1 0
R10-300 R10-300 R10-300 R10-300 R10-300
306 323.4 345.6 25.2
0
1.60 1.60 1.60 1.60 1.60
RM489.60 RM517.44 RM552.96 RM40.32 RM0.00
57
Level Column height
Column size
Num. of Column
Links
Length of links
Rate
Price of Links
3 4 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
29 32 16 4 0
R10-300 R10-300 R10-300 R10-300 R10-300
295.8 470.4 307.2 100.8
0
1.60 1.60 1.60 1.60 1.60
RM473.28 RM752.64 RM491.52 RM161.28
RM0.00 2 4.2 250 x 250
325 x 325 400 x 400 500 x 500 550 x 550
44 34 12 11 1
R10-300 R10-300 R10-300 R10-300 R10-300
448.8 499.8 230.4 277.2 28.2
1.60 1.60 1.60 1.60 1.60
RM718.08 RM799.68 RM368.64 RM443.52 RM45.12
1 5.2 250 x 250 325 x 325 400 x 400 500 x 500 550 x 550
36 33 16 13 4
R10-300 R10-300 R10-300 R10-300 R10-300
465.12 614.46 389.12 414.96 142.88
1.60 1.60 1.60 1.60 1.60
RM744.19 RM983.14 RM622.59 RM663.94 RM228.61
Total 36.4 622 RM14,095.49
5.2.6. Calculation for RC Column’sSteel Coasting (Hooks)
Calculation for RC column’s steel coasting is summarised in Table 5.12 bellow.
Table 5.12: Calculation for RC column’s steel coasting (Hooks)
Level
Column height
(meter)
Column size
Num. of Column
Hooks
Length of hooks
(meter)
Rate
(RM/m)
Price of Hooks
Top
Roof
3 250 x 250 325 x 325 400 x 400
500 x 500
550 x 550
47 6 0
0
0
N/A 4T10-300 4T10-300
2T10-300
6T10-300
0 64.68
0
0
0
1.55 1.55 1.55
1.55
1.55
RM0.00 RM100.25
RM0.00
RM0.00
RM0.00 8 4 250 x 250
325 x 325 400 x 400
500 x 500
550 x 550
37
16 0
0
0
N/A
4T10-300 4T10-300
2T10-300
6T10-300
0
235.2 0
0
0
1.55
1.55 1.55
1.55
1.55
RM0.00
RM364.56 RM0.00
RM0.00
RM0.00 7 4 250 x 250
325 x 325
400 x 400
500 x 500 550 x 550
29 23
1
0 0
N/A 4T10-300
4T10-300
2T10-300 6T10-300
0 338.1
19.2
0 0
1.55 1.55
1.55
1.55 1.55
RM0.00 RM524.06
RM29.76
RM0.00 RM0.00
6 4 250 x 250 325 x 325
400 x 400 500 x 500
550 x 550
26 23
4 0
0
N/A 4T10-300
4T10-300 2T10-300
6T10-300
0 338.1
76.8 0
0
1.55 1.55
1.55 1.55
1.55
RM0.00 RM524.06
RM119.04 RM0.00
RM0.00 5 4 250 x 250
325 x 325 400 x 400
500 x 500 550 x 550
22 17 15
0 0
N/A 4T10-300 4T10-300
2T10-300 6T10-300
0 249.9 288
0 0
1.55 1.55 1.55
1.55 1.55
RM0.00 RM387.35 RM446.40
RM0.00 RM0.00
4 4 250 x 250 325 x 325 400 x 400
500 x 500
550 x 550
30 22 18
1
0
N/A 4T10-300 4T10-300
2T10-300
6T10-300
0 323.4 345.6
12.6
0
1.55 1.55 1.55
1.55
1.55
RM0.00 RM501.27 RM535.68
RM19.53
RM0.00
58
Level Column height
Column size
Num. of Column
Hooks
Length of hooks
Rate
Price of Hooks
3 4 250 x 250 325 x 325
400 x 400
500 x 500
550 x 550
29 32
16
4
0
N/A 4T10-300
4T10-300
2T10-300
6T10-300
0 470.4
307.2
50.4
0
1.55 1.55
1.55
1.55
1.55
RM0.00 RM729.12
RM476.16
RM78.12
RM0.00 2 4.2 250 x 250
325 x 325 400 x 400 500 x 500
550 x 550
44
34 12 11
1
N/A
4T10-300 4T10-300 2T10-300
6T10-300
0
499.8 230.4 138.6
42.3
1.55
1.55 1.55 1.55
1.55
RM0.00
RM774.69 RM357.12 RM214.83
RM65.57 1 5.2 250 x 250
325 x 325
400 x 400 500 x 500
550 x 550
36 33
16 13
4
N/A 4T10-300
4T10-300 2T10-300
6T10-300
0 614.46
389.12 207.48
214.32
1.55 1.55
1.55 1.55
1.55
RM0.00 RM952.41
RM603.14 RM321.59
RM332.20 Total 36.4 622 RM8,456.89
5.2.7. Calculation for RC Column’sSteel Coasting (Total)
Calculation for RC column’s steel coasting is summarised in Table 5.13 bellow.
Table 5.13: Calculation for RC column’s steel coasting (Total)
Level Cost (RM)
TOP ROOF RM11,141.08
8 RM17,160.24
7 RM19,279.10
6 RM20,842.94
5 RM25,462.55
4 RM33,259.68
3 RM39,325.80
2 RM52,445.42
1 RM76,292.03
TOTAL RM295,208.82
5.2.8. Calculation for Staircase’sSteel Coasting
Calculation for RC Staircase’s steel coasting is summarised in Table 5.14 bellow.
Table 5.14: Calculation for RC staircase’s steel coasting
Level
Main rebar
Number of units
Length of rebar
(meter)
Rate
(RM/m)
Price of steel
Top Roof
T10
T12
22
96
396
576
1.55
2.23
RM613.80
RM1,284.48 8 T10
T12
22
96
396
576
1.55
2.23
RM613.80
RM1,284.48
59
Level
Main rebar
Number of units
Length of rebar
(meter)
Rate
(RM/m)
Price of steel
7
T10
T12 22
96 396
576 1.55
2.23 RM613.80
RM1,284.48
6
T10
T12 22
96 396
576 1.55
2.23 RM613.80
RM1,284.48
5 T10 T12
22 96
396 576
1.55 2.23
RM613.80 RM1,284.48
4
T10
T12 22
96 396
576 1.55
2.23 RM613.80
RM1,284.48
3
T10
T12 22
96 396
576 1.55
2.23 RM613.80
RM1,284.48
2 T10
T12 22
96 396
576 1.55
2.23 RM613.80
RM1,284.48
1 T10
T12 22
96 396
576 1.55
2.23 RM613.80
RM1,284.48 Total 1062 6372 RM17,084.52
5.2.9. Calculation for Shear Wall’sSteel Coasting
Calculation for shear wall’s steel coasting is summarised in Table 5.15 bellow.
Table 5.15: Calculation for shear wall’s steel coasting
Shear Wall
Main Rebar / Links
Length
(meter)
Number of Units
Length of rebar
(meter)
Rates
(RM/m)
Price of steel
Dirty Lift
Horizontal bars - T10
Vertical bars - T12
Links - R6
13
38
0.25
366
132
3003
4758
5016
750.75
1.55
2.23
0.56
RM7,374.90
RM11,185.68
RM420.42
Lift 1,2 & 3
Horizontal bars - T10
Vertical bars - T12
Links - R6
25
38
0.25
366
250
5733
9150
9500
1433.25
1.55
2.23
0.56
RM14,182.50
RM21,185.00
RM802.62
Lift 4,5 & 6
Horizontal bars - T10
Vertical bars - T12
Links - R6
25
38
0.25
366
250
5733
9150
9500
1433.25
1.55
2.23
0.56
RM14,182.50
RM21,185.00
RM802.62
Total 40917.25 RM91,321.24
5.3. Pile Caps Price and Calculations
The calculation for the price of pile caps are shown in Table 5.16.
60
Table 5.16: Pile caps price and calculations
PILE GROUP CONCRETE (RM) STEEL (RM)
2 piles
3 piles
4 piles
5 piles
12 piles
15 piles
RM24,300.13
RM5,996.02
RM9,156.57
RM10,190.83
RM10,057.33
RM12,800.24
RM28,915.97
RM5,700.25
RM9,215.46
RM14,321.06
RM14,453.81
RM17,848.68
TOTAL RM72,501.12 RM90,455.23
5.4. Total Cost of Materials
The summary of the cost is represented in Table 5.17 bellow.
Element Price (RM)
Concrete (superstructure) RM1,133,693.11
Steel (superstructure) RM 834,849.18
Concrete (pile caps) RM72,501.12
Steel (pile caps) RM90,455.23
Spun piles RM1,483,399.00
Total RM 3,614,897.64