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

Aim

To analyze and design the RC Shear wall at Grid A-11 in the Structural model and evaluate the longitudinal steel ratio,boundary element length and shear reinforcing ratio from the design results and provide the structural detailing as per IS 13920-2016 standards

Shear Wall Design and Results

1. Check Model

Once the Model and Loading parameter were assigned check the model have any warning messages.

If no warning the model is OK then go for analysis.

2. Shear Design

Once Analysis part become completed then Design the Shear wall

From Display Design Info of Shear wall Design, extract the longitudinal ratio, boundary element and shear reinforcement ration of the design result for A11 Shear Wall

Longitudinal Pier reinforcement

Shear wall Design--> Display Info--> Pier Longitudinal Reinforcing

Pier Edge/Boundary Zones width

Shear wall Design--> Display Info--> Pier Edge/Boundary zones widths

Pier Shear Reinforcing

Shear wall Design--> Display Info--> Pier Shear Reinforcing

Once the values were noted then it should be verified as per IS 13920

Classify the Type of Shear wall

Height of the Shear Wall - 21000mm

The height of the Shear wall is taken from the Etabs Model

For A11 Grid Shear Wall should be Upto Terrace Level i.e the height as 21 m

According to IS 13920:2016 Cl 10.1.4(c)

Slender wall `h_w/L_w>2`

i.e 21000/1500= 14 > 2

As it comes under the type of slender wall, the Minimum reinforcement of RC Shear wall followed with Table 1 (iii) of IS 13920-2016

According to Cl 10.1.8 of IS 13920

The maximum diameter of shear wall shall not exceed 1/10th of the thickness of wall

i.e 300/10= 30mm

Provide 25 mm diameter of bar

The maximum spacing of bar shall not exceed the smaller as per Cl 10.1.9 of IS 13920

(a) 1/5th the horizontal length Lw--> 1500/5= 300 mm

(b) 3 times the thickness of web of wall 3x300 = 900 mm

(c) 450mm

Adopt 300mm spacing for vertical and horizontal

The maximum horizontal reinforcement

The `rho_h`is calculated from Etabs results i.e the Pier shear reinforcing value

(i) `rho_h=0.048

Substitue the value of `rho_h on rho_(h_min)` we get the value as 0.0163

Area of Horizontal reinforcement as 0.0163 x 1500 x 300=7335 Sq.mm

Area of reinforcement for meter height of the wall as 7335/21=349mm^2

(ii) `(rho_(v,be))_min= 0.0080`

For Left Boundary Element the area of reinforcement is 0.008*600*300=1440 Sq.mm

For Right Boundary Element the area of reinforcement is 0.008*450*300= 1080 Sq.mm

(iii) `(rho_(v, n))_min`= 5.525 x 10^ -3 x 300 x 1500 = 2363.5 Sq mm

(iv) Minimum web reinforcement

`rho_(v_(web)= 0.0025`

= 0.0025 x 450 x 300 = 337.5 Sq.mm

Provide 28 nos of 25 dia bars

Boundary element special confinement as per Cl10.4.4 of IS 13920:2016

`A_(sh)`= 0.05 Sv h fck/fy

= 0.05 x 150 x 1000 x 25/415 = 451 Sq.mm

Provide 8mm dia with 2 links at 150 mm c/c and overall shear reinforcement with 8mm dia with 250 mm c/c

Conclusion

Thus the detailed design of RC shear wall and corresponding structural detailing as per IS 13920:2016 were done and verified.