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

1. 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

AIM:- a) To run analysis and design the RCC shear walls for G+6 buildings

b) To extract values of longitudinal steel ratio, boundary element length and shear reinforcing ratio from the design results

c) To provide a cross-sectional steel arrangement of the shear wall from its base up to the terrace in compliance with provisions of IS 13920-2016

d) To provide elevation drawings of the reinforcement details of the shear wall from base up to the terrace

INTRODUCTION:- All the steps are going to be mentioned along with step by step procedure

PROCEDURE:-

• Open ETABS 2020 downloaded file
• Check the model

• Run an analysis
• Go to design > Shear wall design

• Select shear longitudinal reinforcement ratio to check the result of shear wall at grid A-11

• Select pier reinforcing ratio to check the result of shear wall at grid A-11

• Right click on the member to get the design results

a) Calculation of vertical reinforcement:-

Maximum vertical reinforcement from ETABS output = 13128 mm^2

As per the clause 10.1.8. IS 13920-2016 largest diameter of longitudinal steel bars = 1/10*300 = 30 mm

Provide 25 mm longitudinal steel bars

Area of 25 mm bars provided = 490.62 mm^2

Number of bars = 13128/490.62 = 28

2 more additional bars are provided in the boundary element for proper confinement

Total 30 nos of 25 mm dia bars are provided

Wall thickness = 300 mm which satisfies clause 10.1.2 of IS 13920-2016

Length of wall = 1500 mm

hw/lw = 1500/300 = 5> 4 . Hence satisfies clause 10.1.3

Classification of wall : 21/1.5 = 14>2. Hence the wall is classified as slender walls (clause 10.1.4, IS 13920-2016)

Minimum vertical reinforcement ratio as per IS 13920-2016 table 1 (iii)

= 0.0025 + 0.01375*(300/1500) = 5.25*10^-3

Minimum net vertical reinforcement = 5.25*10^-3*300*1500 = 2362.5 mm^2

Minimum vertical reinforcement within boundary element,

Width of boundary element for left side as per ETABS result = 600 mm

Minimum vertical reinforcement on width boundary element for left side = 0.0080 * 600 * 300 = 1440 mm^2

Width of boundary element for right side as per ETABS result = 450 mm

Minimum vertical reinforcement on width boundary element for right side = 0.0080 * 600 * 450 = 1080 mm^2

As per clause 10.1.9 maximum spacing of vertical reinforcement is given below:-

1. 1/5*1500 = 300 mm

2. 3*300 = 900 mm

3. 450 mm

Provide spacing of vertical reinforcement = 100 mm

b) Calculation of horizontal reinforcement

= 0.0025 + 0.5*(21000/1500-2)*((750/1000*300)-0.0025) = 0.0025+0 = 0.0025

Minimum horizontal reinforcement for every 1 m height of the wall in shear wall = 0.0025*300*1000 = 750 mm^2

Spacing of confining reinforcement a sper clause 10.4.4

1. 1/3*300 = 100 mm

2. 6*25 = 150 mm

3. 150 mm

Maximum spacing provided = 150 mm for boundary element

= 200 mm for not boundary element

= 0.05 * 150 * 1000 * 25/ 415 =452 mm^2

c) Detailing of shear wall from AutoCAD

Fig : Cross Sectional Details

Fig : Elevation Details

RESULTS:- The following results are been illustrated properly

a) Run analysis and design the RCC shear walls for G+6 buildings

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

c) Provide a cross-sectional steel arrangement of the shear wall from its base up to the terrace in compliance with provisions of IS 13920-2016

d) Provide elevation drawings of the reinforcement details of the shear wall from base up to the terrace