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

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: -

Run the analysis and design the RCC shear walls.

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.

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

procedure:

• open the etabs model which are attached in the challenge

• we have to design shear wall of crossing gridA,11.
• so, change into plan view and keep it all stories select gridA,11
• click right button > click selected objects only

• should check pier assignments are done for all or not
• view display options> other assignments>click labels>click ok.

• pier assignments are done for all go back and uncheck it. and,
• Run Analysis

• Click shear wall design option

• pier longitudinal reinforcement or vertical reinforcement values

• pier shear reinforcing or horizontal reinforcing values

• pier edge/ boundary zone widths values

elevation details:

Detailing guidelines for shear wall:

• minimum reinforcement for shrinkage & 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

h/L= 21000/1500 = 14 > 2

Minimum net vertical reinforcement as per IS-13920-2016 Table-1: (iii)

=0.0025 + 0.01375 (thickness of wall/length of wall)

=0.0025 + 0.01375 (300/1500)

It is taken as 2363 mm2

Minimum vertical reinforcement within boundary element Table-1 (iii)

• 1440 mm2 on left (600mm width boundary element)
• 1080 mm2 on right (450mm width boundary element)

Minimum horizontal reinforcement in shear wall as per IS-13920-2016 Table-1 (ii)

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

Ph = 750/(300x1000) = 0.0025, hw = 21000, Lw = 1500

(Ph)min = 0.0025 + 0.5 (21/15 - 2) x 0

(Ph)min = 0.0025, which is the same 750 mm2/m

Maximum diameter of rebar for shear wall as per IS-13920-2016 clause 10.1.8

1/10th of wall thickness = 300/10 = 30 mm

Commercial rebar diameter 25 mm shall be adopted

2 additional boundary element bars of 12 mm diameter are provided

Confining reinforcement spacing for boundary element as per IS-13920-2016 clause 10.4.4
(i) 1/3 of minimum member dimension = 300/3 = 100 mm
(ii) 6 times smallest main rebar = 6x25 = 150 mm
(iii) 150 mm permissible if vertical bars are spaced at maximum 200 mm

maximum spacing of confining reinforcement in boundary element 150 mm

Confining reinforcement within boundary element as per IS-13920-2016 clause 10.4.4

Ash = 0.05 x sv x h x (fck/fy)

sv = 150 mm, h = 1000 mm

Ash = 452 mm2