Analysis and Design of S Shaped

Commercial Office Tower

Under the Guidance:

Dr. Nirjhar Dhang

Group S (M.tech)

1. Somraj Biswas (14CE65R01) 2. Saudip Sahu (14CE65R13) 3. Zankar Sanket D. (14CE65R29) 4. Sachin Y. Rangari (14CE65R31)

High Rise Structures

Department of Civil Engineering Indian Institute of Technology, Kharagpur

Analysis and Design of S Shaped Commercial Office Tower

1

Contents

Chapter 1. Drawings

Chapter 2. Area Statement

Chapter 3. Calculation of Column and beam cross

section Chapter 4. Earthquake Load Calculation

Chapter 5. Analysis of the Frame and checks

Chapter 6. Design of Beams and Columns

Analysis and Design of S Shaped Commercial Office Tower

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Chapter 1. Drawings

General Layout

Analysis and Design of S Shaped Commercial Office Tower

3

Column Spacing

Floor Plan

Analysis and Design of S Shaped Commercial Office Tower

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Chapter 2. Area Statement

Area Calculation

Foot Print Area =90*60-2*0.5*20*10-0.5*20*20-2*10*20=4600 sq.

Carpet Area at Each Floor =footprint area 829.5m2=3770.5m2 Total carpet area req. = 150000 sq.m

Total Area for Lifts No. of lifts provided=20 Total Area required for lifts=20*(2*5)=200Sq.m

Total column area Total No. of columns provided=62 Area occupied by columns=62*2*2=248sq.m

Area of staircases

No. of staircases provided=10

Total area of staircases=10*2*5=100Sq.m

Washroom area No of washrooms=5

Total area of all washrooms=5*4*5=100Sq.m

Wall Area

Thickness of outer wall=0.25m

Thickness of inner wall=0.2m

Total area occupied by walls= 181.5Sq.m

Specifications

Floor Carpet Area = 3770.5m2

Carpet Area= 150000 m2

Structural form adopted - Rigid Frame Footprint Area= 4600sq.m (

Chapter 3. Calculation of Column and beam cross section

Load Calculations for typical floors

Dead Load Self wt. of slab=10.00 KN/m Floor Finish=4KN/m

Self Weight of beam=5.25KN/m

Load From Walls=19 KN/m

Live Load Let us assume, L.L=10KN/m Total Factored UDL=1.5*(DL + LL) = 1.5*(38.25 +10) =72.375 KN

Column positions & Load Calculation

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Load Acting on Critical Frame

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Load On Columns

Assuming the columns to be square columns of size 2m

Column load per floor=22254

=400KN

Load on C1(outer column)=(3(wl/2) +400) no of storeys

=(3289.5+400) 40

=50740KN

Load on C2(inner column)=(4(wl/2)+400) no of storeys

=(4289.5+400) 40

=62320KN

Dimensions of Columns OUTER COLUMN

Pu=0.4fck0.96Ag+0.67fy0.04Ag

Here the reinforcement considered is 4% of the gross area

5074010^3=0.4350.96Ag +0.674150.04Ag

Ag=2065792.69mm2

Since we have considered the column to be square

Size of the column=1.431.43m

INNER COLUMN

Pu=0.4fck0.96Ag+0.67fy0.04Ag

Here the reinforcement considered is 4% of the gross area

6232010^3=0.4350.96Ag +0.674150.04Ag

Ag=2537252.67mm2

Since we have considered the column to be square

Size of the column=1.61.6m

Column size considered in the design is taken to be 2m which is safe

REINFORCEMENT

OUTER COLUMN

Ast1 = 0.042065793=82631.68 mm2

No of 32mm reinforcement =102.74=103

INNER COLUMN

Ast2 = 0.04 2537252 = 101490 mm2

No of 32mm reinforcement =126.23=127

Chapter 4. Earthquake Load Calculation

Earthquake Load Calculation Given : Building Located in Kolkata Zone III Z=0.16 Table 2 of IS: 1893

I=1.5 Table 6 of IS:1893

R=5.0 Table 7 of IS: 1893 Part 1

Floor Area =4600 sq.m Live Load=10KN/m

Wt. of individual Floors W1=W2W39=4600*(9.69*5*0.5)

=56093.2 KN

Wt. of top Floor W40=4600*(5.521)=25397.46 KN

Total Weight =56093.2*39+25397=2213024KN

Fundamental period

T = 0.09h / sqrt(d) Clause 7.6.2. of IS: 1893 Part 1

Along X direction=0.09*207/sqrt(48)=2.689 seconds Sa/g=0.505

Along Y direction=0.09*207/sqrt(120)=1.7 seconds Sa/g=0.8

Design horizontal Seismic coefficient Ah Along X direction=0.01216 Along Y direction=0.0192

IN X DIRECTION

T(in X direction)=0.09h/d

=0.09160/60

=1.85 sec

Assuming the building to be constructed in zone 2

Z=0.1 I=1.5 R=5

From the graph we can find Sa/g =0.8

Ah=(ZI/2R) Sa/g=0.012

So design base shear in X direction =AhW

=26556.3 KN

IN Y DIRECTION

T(in Y direction)=0.09h/d

=0.09160/90

=1.518 sec

Assuming the building to be constructed in zone 2

Z=0.1 I=1.5 R=5

From the graph we can find Sa/g =0.7

Ah=(ZI/2R) Sa/g=0.0105

So design base shear in Y direction =AhW

=23237 KN

Chapter 5. Analysis of the Frame and checks G+40 storey

Chapter 6. Design of Beams and Columns

Design of Composite Beams:

Given Data: The Bending Moment and Shear force was obtained from OpenSees:

Maximum Bending Moment ( M ) = 1123.23 KN-m Maximum Shear Force ( V ) = 578.101 KN

Span = 8 m

beff = span/4 = 2.00 m

Assumed Data: The Composite Beam Properties are:

Grade of Concrete ( fck ) = M 30 Grade of Steel ( Fy ) = Fe 250

Steel Section Used = ISMB 500

Position of Plastic Neutral Axis: Ds=150mm

Aa=11100mm2

Dc=325mm

= 20.1 Aa=223110 beffds =2000*150=300000

Plastic neutral axis lies in slab

Plastic Moment Capacity:

Xu= Aa/ beffds Mp=0.87*fy*Aa(250 +150 -0.42Xu) = 1275.08KN-m >1123 Hence section is safe.

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Design of Column 1:

Given Data:

INTERNAL Columns The Axial force and moments was obtained from Open Sees:

Maximum Axial Load ( P ) Maximum Bending Moment (Mz1) Maximum Bending Moment(Mz2)

=46315 KN-m =1755.5KN-m =-1132 KN-m

Aa=15600 sq.mm As=1256 sq.mm Ac=3983144 sq.mm Plastic resistance of concrete= Aafy + Ac*(fck)cu + Asfsk 62510KN > 62320 KN So safe

EXTERNAL COLUMNS

Maximum Axial Load ( P ) Maximum Bending Moment (Mz1) Maximum Bending Moment(Mz2)

=46315 KN-m =1755.5KN-m =-1132 KN-m

Aa=15600 sq.mm As=1256 sq.mm Ac=3983144 sq.mm Plastic resistance of concrete= Aafy + Ac*(fck)cu + Asfsk 62510KN > 50740 KN So safe