Challenge

Project 1

SSomasundaram D10 Oct 2022

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Aim:

To design a multi-story Residential Building located in Bangalore using STAAD Pro Connect Edition.

Procedure:

Unit weight of the materials

Reinforced Cement Concrete = 25kNmm3

Plain Cement Concrete = 24kNmm3

Cement Concrete Screed = 20kNmm3

Cement Masonry Units = 22kNmm3

Structural Steel = 78.5kNmm3

Soil = 18kNmm3"

Dead Load

Floor slab

Slab weight = 3.75kNmm2

Partitions = 1.5kNmm2

Floor Finish = 2.5kNmm2

Miscellaneous = 1kNmm2

Total Floor Load = 8.75 kNmm2

Roof slab

Slab weight = 3.75kNmm2

Insulaions and Water Proofing = 0.5kNmm2

MEP Services = 0.5kNmm2

Miscellaneous = 0.5kNmm2

Total Roof Load = 5.25kNmm2

Live Load

Floor slab

Common Corridor = 3kNmm2

Total Floor Load = 3kNmm2

Roof slab

Accessible Roof = 1.5kNmm2

Total Roof Load = 1.5kNmm2

Design of Slab

Span Shorter Direction (Clear) ly = 3.125.00 m

Span Longer Direction (Clear) lx = 5.500 m

Live Load on the Slab LL= 3.00 kN / m2

Compressive stength of concrete fck = 40 N / mm2

Yield strength of steel fy = 415 N / mm2

Unit weight of concrete Ƴ = 25.00 kN / m3

Unit weight of floor finish 100 mm Ƴ= 22.00 kN / m3

Clear concrete cover =25.00 mm

Bearing of slab B=250.00mm

Step 1

Cl 24.1

Span to effective depth ratio l/d = 32

Minimum effective depth d = 97.66 mm

Overall depth D = 127.66 mm

Provide Overall depth D = 150.00 mm

Dia of bars for short direction Φ=10mm

Dia of bars for long direction Φ = 10 mm

Effective Depth d=120.00mm

Loading on the slab

Dead Load of the slab (DL) 3.75.00kN / m2

Super Dead Load = 5.00 kN / m2

Live Load on the slab=3.00 kN / m2

Total Load on the slab (TL) =12.00kN / m2

Design Load = (Total Load x Load Factor i.e. 1.5) ie 18.00 kN / m2

Effective Span lx = 5.17 m

ly=5.17 m

Ratio ly/lx= 1.000 Two Way

T26/27

1.0 ax 1.10 ay

For negative moments (at top) 0.047 0.047 0.053 0.047

For positive moments (at bottom) 0.035 0.035 0.045 0.035

Step 2

BM per unit width of slab Mx = ax w lx2 My = ay w lx2

For negative moments (at top) 22.60 22.60KN-m/m

For positive moments (at bottom) 16.83 16.83nKN-m/m

Shear force , V 0.5wlx 46.52kN/m

Step 3

To check the effective depth of slab

Mu,lim = 0.138fckbd2

d=63.99 mm

Step 4

Depth of slab for shear force

T20 τc,max =4N/mm2

τc=0.3

Cl 40.2.1 k=1.2D=200mm

τc=0.36 N/mm2

τv=Vu / bd

=0.28N/mm2

τv">τvτv < τc < τc,max

0.28 0.36 4

SAFE

Step 5

Determination of areas of steel

Mu = 0.87fyAstd(1-Astfy/fckbd)

For Negative moments Mu Top = 22.60

Ast = 463.99 mm2/m

For Positive moments Mu Bot = 16.83

Ast = 345.52 mm2/m

Step 5.1

Determination of distribution steel

Astmin =0.12bd

202.8mm2

Step 5.2

Selection of reinforcing bars

Area of bars (Top steel) =113.04mm2

Spacing =244

=240mm

Provide 12mm bars at a spacing 240mm

Area of bars (Bottom steel=113.04mm2

Spacing =327

=300mm

Provide 12mm bars at a spacing 300mm

Calculation of wind load

Design Wind Speed Vz =Vb k1 k2 k3 k4 m/s

Basic Wind Speed (Banglore) Vb =33 m/s

Probability factor k1 = 1

Terrain factor , Category for k2 =Category 4 B

Topography factor k3= 1

Design Wind Pressure Pz=0.6 Vz2

Height k2 Vz Pz Pz in kN

3.5 0.76 25 377.40 0.96

7.0 0.76 25 377.40 0.96

10.5 0.76 25 377.40 0.96

14.0 0.76 25 377.40 0.96

17.5 0.76 25 377.40 0.38

21.0 0.78 26 397.93 0.43

24.5 0.84 28 461.04 0.46

Calculation of seismic load:

Design Base Shear VB = Ah W kN

Design Horizontal Acceleration Coefficient Ah = {(Z/2) x (Sa/g)}/(R/I)

Zone factor Z = 0.1 (Banglore)

Soil Condition factor , Sa / g

T=0.09h/">√d

Height of building h=24.5m

Base dimension of building Along X = 16

Along Z = 25

T along X =0.5513s

T along Z =0.4410s

Sa / g =1.814 Along X

Sa / g =2.268 Along Z

Response Reduction Factor R = 3

Importance Factor I= 1.2

Horizontal Acceleration Coefficient Ah = 0.0363 Along X

Ah =3.68%

Seismic Weight

Area of Each floor A = 400m^2

Due to Dead Loads , Typical Floor DL = 12kN/m^2

W DL = 5000kN

Due to Dead Loads ,Roof DL roof =9kN/m^2

=3600kN

Due to Live Loads , Typical Floor LL = 3kN/m^2

W LL = 300kN

Due to Live Loads , Roof LL = 1.5kN/m^2

W LL =0

Total Seismic Weight W = 35400kN

Design Base Shear VB = 1284.35kN

Horizontal acceleration cofficient Ah= 0.0454 Along Z

=4.54%