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

Aim:

To run the analysis and design the RCC shear walls shown in the etabs model.

Procedure:

• Open the Etabs file and run the analysis.
• After the analysis click shear wall design.

                      

• Select display info and choose PM failure.

                     

• Now select longitudnal reinforcement:go to concrete frame design and click display design info.
• Choose pier longitudnal reinforcing.

                              

                              

• Shear reinforcement: go to concrete frame design and click on display design info and choose Shear reinforcing.

                              

• Boundary element width: go to concrete frame desogn.click display design info,choose pier edge or boundary zone width.

                             

 

Calculations with IS13920-2016:

a) Overall height of wall h=21000mm,length of wall L=1500mm.

Ratio(h/L)=21000/1500=14>2 

So the given RC wall is slender.

b) According to clause 10.1.8 the largest diameter that can be used in RC wall should not exceed 1/10th of thickness of wall:

So thickness of wall=300mm

Therefore,300/10=30mm.

We used 25mm dia rebar in the detailing.So it is within limit.

c) According to clause 10.1.9 maximum spacing of longitudnal/transverse rebar should not exceed:

i) 1/5th of horizontal length=1500/5=300mm

ii) 3 times of thickness(tw)=3x300=900mm

iii) 450mm

So we need to adopt spacing of 300mm both for vertical and horizontal rebar inside RC wall.

d) Minimum horizontal reinforcement calculation as per table 1 of IS13920-2016:

(Ph)min=0.0025+0.5(hw/Lw-2)(Ph-0.0025)

=0.01672of cross section of RC wall

=1500*300*0.01672

=7524 sq.mm for entire RC wall height,which will be  358 sq.mm/meter height of RC wall

We provided 16mm dia at 100mm c/c which gives =1000/100x2x201=4020sq.mm

e) Minimum boundary reinforcement calculation as per table 1 of IS 13920-2016

(Pv,be)min=0.008

=0.008x300x300=720sq.mm

We provided 8 numbers 12mm dia rebar=8x113=904 sq.mm

f) Minimum web reinforcement calculation as per table-1 of IS13920-2016

(Pv,web)min=0.0025

=0.0025x900x300=675 sq.mm

we provided 8 numbers 12mm dia rebar=8x113=904 sq.mm

g) Minimum overall RC wall vertical reinforcement calculation as per table 1 of Is13920-2016

(Pvnot=t)min=0.0025+0.01375(tw/Lw)

=0.00525 times of wall cross section

=0.00525x1500x300=2363 sq.mm

We provided 24 numbers 12mm dia rebar=24x113=2712sq.mm

h) Boundary element special confining reinforcement as per clause 10.4.4 of IS13920-2016:

Ash=0.05xSvxh(Fck/fy)

As per drawing maximum spacing of confinement is 100mm.

h= minimum clear distance between longitudnal rebar=150mm 

So Ash=45sq.mm

We already provided two closed links of 16mm dia=2x201=402 sq.mm

Conclusion:

We have designed the specified RC wall and also the clauses from ductility code IS13920-2016 are verified for the RC wall detailing.