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

Aim: To provide cross sectional steel arrangement of the shear wall using design results in ETABS and sketch the elevation drawings of the reinforcement details.

Introduction: ETABS is an engineering software product that caters to multi-story building analysis and design. Modeling tools and templates, code-based load prescriptions, analysis methods and solution techniques, all coordinate with the grid-like geometry unique to this class of structure.

Procedure:

Step 1:

• Open Lecture9 challenge etabsFile - file from the question in ETABS 

• Select shear wall at grid A-11

Step 2:

• Right click and select Show Selected Objects Only

• Click elevation along grid 11

 

 Step 3:

• Click 'Run Analysis' from top menu

• Click Shear Wall Design from top menu

 Step 4:

• Click 'Display Design Info' in the 'Shear Wall Design' option from the top menu

• Select Pier Shear Reinforcing as design output

Step 5:

• Click 'Display Design Info' in the 'Shear Wall Design' option from the top menu

• Assign 'Pier Edge/Boundary Zones Widths' as design output and click OK

• Story data is given below for further study

 Guidline with IS13920-2016:

a) Overall height of wall h - 21000mm, Length of wall L - 1500mm

Ratio (h/L) -21000/1500 - 14 > 2, The given RC wall is slender.

b) The largest diameter than can be used in RC wall should not exceed 1/10th of thickness of wall. So 300/10 = 30mm

We used 25mm dia rebar in the detailing. OK.

c) The maximum spacing of longitudinal / transverse rebar should not exceed

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

(ii) 3 times of thickness (t) = 3 x 300 = 900mm

(iii) 450mm

So have to adopt maximum 300mm spacing both for vertical and horzontal rebar inside RC wall.

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

 (ρh)min</math>">(ρh)min
= 0.0025 + 0.5(hwLw-2)(ρh-0.0025)</math>">(hwLw−2)(ρh−0.0025)

= 0.01672 of cross section of RC wall

= 1500 x 300 x 0.01672 = 7524 sq.mm for entire RC wall height.

= 7524 / 21 = 358 sq.mm /m height of RC wall

 already provided 16mm dia at 100 mm c/c spacing which will give = 1000/100 x 2 x 201 = 4020 sq.mm (OK).

e) Minimum boundary reinforcement calculation as per Table-1 of IS13920-2016

(ρv,be)min</math>">(ρv,be)min

= 0.008

= 0.008 x 300 x 300 = 720 sq.mm

already provided minimum 8 numbers 12mm dia rebar = 8 x 113 = 904 sq.mm ( Hence OK )

f) Min web reinforcement calculation as per Table-1 of IS13920-2016

(ρv,web)min</math>">(ρv,web)min
= 0.0025

= 0.0025 x 900 x 300 = 675 sq.mm

already provided minimum 8 numbers 12mm dia rebar = 8 x 113 = 904 sq.mm ( hence ok )

g) Minimum overall RC wall vertical reinforcement calculation as per Table-1 of IS13920-2016

(ρv,≠t)min</math>">(ρv,≠t)min = 0.0025 + 0.01375 (twLw)</math>">(twLw)

= 0.00525 times of wall cross section

= 0.00525 x 1500 x 300 = 2363 sq.mm

already provided minimum 24 numbers 12mm dia rebar = 24 x 113 = 2712 sq.mm ( hence ok )

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

Ash=0.05Svh(Fckfy)</math>">                               Ash=0.05Svh(Fck / fy)

Max spacing of confinement is 100mm as per drawing

h = minimum clear distance between longitudinal rebar = 150mm

Ash=</math>">Ash=45 sqmm

already provided two closed links of 16mm dia = 2 x 201 = 402 sq.mm ( hence ok )

• Using AutoCad, elevation drawings of the reinforcement details of the shear wall is drawn below

Shear Wall at Grid A-11

 .

Conclusion: Thus we have designed the specified wall and Also the clauses from ductility code Indian standard IS13920-2016 are verified for the RC wall detailing.

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