Analysis & Design of RCC shear walls in the model using ETABS

Aim:

• To extract values of longitudinal steel ratio, boundary element length and shear reinforcing ratio from the design results
• To provide cross sectional steel arrangement of the shear wall from its base up to terrace, in compliance with provisions of IS 13920 – 2016.
• To provide elevation drawings of the reinforcement details of the shear wall from base up to terrace.

Procedure:

• Download and open the Etabs file attached in the given question
• Check model and Run analysis is done
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• Select Display Menu bar and select Show tables and select Modal Participating Mass ratio and click ok
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• Now the table appears
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• Select Display Menu bar and select Show tables and select Base reaction and click ok
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• Select Properties from Select option from the Select Menu bar and select Wall section, we selected Wall 300 (as given in the question)
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• Now right click and select view only selected item
• Now from Design Menu bar, select Shear wall design and select Start design/ check
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• Now select Display Design info from Design menubar > Shear wall design and select Piers reinforcement ratio in Design output
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• Select Display Design info from Design menubar > Shear wall design and select Piers Edge/Boundary Zone widths in Design output
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• Select Display Design info from Design menubar > Shear wall design and select Piers Reinforcing Ratio in Design output
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• Now Right click on the shear wall and the design will be available like as shown below
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Shear Wall Calculations:

• Base floor to First floor:

Lets assume a Slender wall since height/length ratio is greater than 2.

That is, we have , height of the wall,H = 2100mm and Length of the wall,L =1500mm. Thickness , T = 300mm

P_{h = 0.0297*1500*300 =13365}

Now, Minimum Horizontal Reinforcement ,(P_h)_min = 0.0025 + 0.5 ( H/L- 2) (P_h- 0.0025) = 0.76

Minimum Vertical Reinforcement ,(PV)_{min = 0.0025 + 0.01375 (T/L) = 0.0052}

Longitudinal reinforcement

Using ETABS, the required Rebar Area = 13128 mm²

Minimum Vertical reinforcement , P_v = 13128/ (1500*300) = 0.0297 > 0.0080

From IS 13920:2016,

A_sh = 0.05 *S_v * H * f_ck/f_y

Assuming minimum number of bars as 8, thus A_sh = 50.24mm²

50.24 = 0.05*100*H * (25/100)

Therefore, H= 200.98

Considering 25mm dia bars, Number of bar = 13128/ area of 25mm dia bars = 13128/490.87 = 28 bars

Therefore, 28 number of 25mm dia bars are provided

Shear Reinforcement

Assuming 2 legged 8 mm dia bars at 100 mm c/c

A_sh= 2* Area of 8mm dia bar/ 0.100 = 1005.3 > 750mm²

Thus satisfying the shear reinforcement

• First floor to Second floor:

Longitudinal reinforcement

Using ETABS, the required Rebar Area = 8273mm²

Minimum Vertical reinforcement , P_v = 8273/ (1500*300) = 0.018 > 0.0080

From IS 13920:2016,

A_sh = 0.05 *S_v * H * f_ck/f_y

Assuming minimum number of bars as 8, thus A_sh = 50.24mm²

50.24 = 0.05*100*H * (25/100)

Therefore, H= 200.98

Considering 20mm dia bars, Number of bar = 8273/ area of 20mm dia bars = 26 bars

Therefore, 26 number of 20mm dia bars are provided

Shear Reinforcement

Assuming 2 legged 8 mm dia bars at 100 mm c/c

A_sh= 2* Area of 8mm dia bar/ 0.100 = 1005.3 > 750mm²

Thus satisfying the shear reinforcement

• Second floor to Terrace:

Longitudinal reinforcement

Using ETABS, the required Rebar Area = 4896 mm²

Minimum Vertical reinforcement , P_v = 4896/ (1500*300) = 0.01 > 0.0080

From IS 13920:2016,

A_sh = 0.05 *S_v * H * f_ck/f_y

Assuming minimum number of bars as 8, thus A_sh = 50.24mm²

50.24 = 0.05*100*H * (25/100)

Therefore, H= 200.98

Considering 16mm dia bars, Number of bar = 8273/ area of 16mm dia bars = 26 bars

Therefore, 26 number of 16mm dia bars are provided

Shear Reinforcement

Assuming 2 legged 8 mm dia bars at 100 mm c/c

A_sh= 2* Area of 8mm dia bar/ 0.100 = 1005.3 > 750mm²

Thus satisfying the shear reinforcement