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

To complete the detailed reinforcement design of an RCC shear wall at grid A-11 (size: 300 × 1500 mm) for the G+6 building ETABS model, follow the steps below.

This includes:

• Running analysis & design in ETABS 2018

• Extracting design outputs: longitudinal steel ratio, boundary element length, shear reinforcement ratio

• Providing cross-sectional and elevation reinforcement detailing as per IS 13920:2016

• Drafting reinforcement using AutoCAD or by hand

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✅ STEP 1: Open & Analyze ETABS Model

1.1 Open ETABS Model

• Load the G+6 building ETABS .edb file.

• Locate the shear wall at grid A-11. Ensure it’s assigned as a "Wall Pier" in ETABS.

1.2 Assign Shear Wall Properties

• Check that the wall has the correct thickness (300 mm) and length (1500 mm).

• Material grade:

  • Concrete: M30 (or as defined)

  • Steel: Fe415 or Fe500

1.3 Assign Design Preferences

• Use IS 456:2000 for concrete design

• Enable ductile design checks as per IS 13920:2016

  • Go to Design > Shear Wall Design Preferences

  • Enable special confinement zones and ductile detailing

1.4 Run Analysis and Design

• Run complete analysis

• Then go to: Design > Shear Wall Design > Start Design/Check of Shear Wall

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✅ STEP 2: Extract Key Design Values from ETABS

After design is complete, extract the following for wall at grid A-11:

2.1 Longitudinal Steel Ratio (ρₗ)

• Go to Display > Show Tables > Design > Shear Wall Reinforcement

• Look for Longitudinal Reinforcement Ratio (ρₗ)

  • Acceptable range (per IS 13920): 0.0025 to 0.006

  • For ductile walls: 0.25% to 0.6% of gross area

2.2 Boundary Element Length

• Look in the same design table OR check manually:

  • Clause 10.4.2 of IS 13920:2016 requires boundary elements when:

    • Extreme fiber compressive stress $> 0.2f_{ck}$

  • Length of boundary zone often taken as 1/10 to 1/6 of wall length

    • For 1500 mm wall: boundary zone length ≈ 250–300 mm (each side)

2.3 Shear Reinforcing Ratio (ρₜ)

• Look for: Transverse Reinforcement Ratio (ρₜ)

  • IS 13920 clause 11.3 recommends:

    • Horizontal & vertical reinforcement ratio ≥ 0.0025

    • Reinforcement should be in two layers (face A & B) for walls > 200 mm thick

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✅ STEP 3: Cross-Sectional Detailing of Reinforcement

3.1 General Guidelines (IS 13920 – 2016)

Longitudinal Bars (Vertical)

• Main flexural reinforcement

• Use T16 to T25 bars spaced at 100–200 mm c/c

• Provided equally on both faces

Horizontal Reinforcement

• Use 8 mm or 10 mm bars

• Minimum: 0.0025 × area

• Provided on both faces, tied to verticals

Boundary Elements

• Confined zones at ends

• Extra longitudinal bars + closely spaced stirrups

• Stirrup spacing:

  • 100 mm c/c max (IS 13920:2016)

  • Vertical length of confinement = lₒ = larger of:

    • 1/6 clear height of wall

    • 450 mm

    • Twice wall thickness

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3.2 Example Cross-Sectional Detailing (For 300 × 1500 mm Wall)

• Vertical reinforcement:

  • 12 nos. of 20 mm bars (6 per face) @ ~150 mm c/c

• Horizontal reinforcement:

  • 8 mm dia bars @ 150 mm c/c (both faces)

• Boundary element zones (each end 250 mm wide):

  • 4 × 20 mm bars per boundary

  • Stirrups: 8 mm dia @ 100 mm c/c in vertical confinement length

📏 Cover: 25–40 mm

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✅ STEP 4: Elevation Detailing (Base to Terrace)

Prepare an elevation drawing of the shear wall showing:

• Full height of the wall (G+6)

• Zones of special confinement at:

  • Wall base

  • Floor levels (if large moment zones)

• Lapping zones for vertical bars:

  • Preferably staggered

  • Not within confinement zones

• Reinforcement continuity:

  • Boundary elements from base to terrace

  • Uniform or tapered longitudinal bars

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✅ STEP 5: Drafting in AutoCAD or Hand Sketch

Components to Draw:

1. Cross Section

   • Show:

     • Bar layout (vertical + horizontal)

     • Boundary elements

     • Concrete cover

     • Dimensions (300 mm × 1500 mm)

2. Elevation View

   • Show:

     • Wall height across 6 floors

     • Confinement zones at base and levels

     • Vertical bars lapped & continued

     • Horizontal bar spacing

Naming Conventions:

• Use B1, B2, H1, etc. for rebar types

• Include reinforcement table with:

  • Bar diameter

  • Number of bars

  • Spacing

  • Lengths

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✅ Example Reinforcement Summary Table

Bar Type	Location	Dia (mm)	Spacing (mm)	Notes
Vertical	Entire wall (both faces)	20	150	Main flexural reinforcement
Horizontal	Entire wall (both faces)	8	150	Shear & crack control
Boundary Verticals	Each end (250 mm zone)	20	—	4 bars per end
Boundary Ties	Each end	8	100	Confined length = 900 mm at base

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✅ Final Notes

• Confirm reinforcement values with ETABS output

• Check detailing meets IS 13920:2016 clauses 10 & 11

• For high seismic zones (Zone IV/V), boundary detailing is mandatory