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

AIM OF THE CHALLENGE:

• To know the design of RC Shear wall using ETABS analysis.
• To know the basics of shear wall reinforcement detailing with respect to primary standards.
• To ensure the ductility reinforcement required by IS- 13920- 2016 been satisfied in reinforcement drawing.

GIVEN DATA:

The ETABS file for a G+6 building is provided. Run the analysis and design the RCC shear walls (show in the ETABS model). The following challenge deals specifically with the shear wall of size 300x1500 at grid A-11 in the structural model.

• Extract values of longitudinal steel ratio, boundary element length and shear reinforcing ratio from the design results.

• Provide cross sectional steel arrangement of the shear wall from its base up to terrace, in compliance with provisions of IS 13920 – 2016. AutoCAD application can be used for this exercise. Alternatively, it can be drawn by hand as well.

• Provide elevation drawings of the reinforcement details of the shear wall from base up to terrace.

PROCEDURE:

• Open the given file.
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• Save as Shear wall 300X1500@ A-11.
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• Change the plan view to Terrace and select the shear wall on the grid A-11 and keep All stories in the status.
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• Right click and select -Show selected objects only.
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• Go to elevation and select grid A-11 and keep All stories in the status.
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• To view the pier assignments:
• Select set display option -> other assignments -> Labels
• Click apply which will display the label as P1.
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• Uncheck the Label if necessary.
• Run the analysis.
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• Vertical reinforcement, Boundary width and horizontal reinforcement of shear wall at Grid- A11 of size 300X1500 from ETABS:
• Shear wall design:
• Click Shear wall design icon.
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• Pier shear reinforcing:
• Select Shear wall design ->Display shear info -> Pier shear reinforcing
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• Boundary zone width:
• Select Shear wall design ->Display shear info -> Pier edge/ Boundary zone width.
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• Click Edit -> Edit stories and grid systems -> Modify/ Show data.
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• Elevation detail for shearwall:
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Detailing guideline for shear wall:

If any one of the below conditions is required, then it should be included in RC Column design.

• Minimum reinforcement for shrinkage and temperature.
• Ultimate limit state design rebar requirement.
• Ductility rebar requirement.
• Classification of shear wall as per IS- 13920- 2016 clause 10.1.4
• Slender wall:
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• 21000/ 1500 = 14 > 2.
• Minimum net vertical reinforcement as per IS- 13920 -2016 Table-1 (iii)
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• =0.0025 + 0.01375 (300/1500)
• = 2363 mm
• Minimum vertical reinforcement within boundary element Table-1 (iii)
• =0.0080* 600*300=1440mm² on left (600mm width boundary element).
• =0.0080* 450*300=1080 mm² on right (450mm width boundary element).
• Minimum horizontal reinforcement in shear wall as per IS- 13920 -2016 Table-1 (iii)
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• P_h= 750/(300x1000) = 0.0025, h_w = 21000, L_w = 1500
• (p_h)_min= 0.0025 + 0.5(21/15 -2) x0
• =0.0025 which is the same as 750mm²/m
• Maximum diameter of rebar for shear wall as per IS- 13920 -2016 clause 10.1.8
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• 1/10^th of wall thickness= 300/10 =30mm
• Commercial rebar diameter 25mm shall be adopted.

Detail guidelines for shear wall:

• Confining reinforcement spacing for boundary element as per IS- 13920 -2016 clause 10.4.4
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• 1/3 of minimum member dimension= 300/3=100mm
• 6 Times smallest main rebar= 6x25 =150mm
• Maximum spacing of confining reinforcement in boundary element 150mm
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• S_v =150mm, h= 1000mm
• A_sh =452mm²

RESULT:

• For the Shear wall design 25MM dia is used as main bar and 8MM dia bar is used as stirrups.
• 2 Additional main bars at the center is provided to give additional strength to the boundary width.
• Hence it satisfies all the requirement as per the code IS 13920: 2016 as shown above.
• The Shear wall drawing is shown below.
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