The design capacities of the section against shear force in major- and minor-axis directions are evaluated as per section 8.4 of the code, taking care of the following phenomena:
Nominal Plastic Shear Resistance
Resistance to Shear Buckling
Shear area of the sections are calculated as per sec. 220.127.116.11.
Nominal plastic shear resistance is calculated as per sec. 8.4.1.
Among shear buckling design methods, Simple post-critical method is adopted as per sec. 18.104.22.168(a).
Working Stress Design
The actual shear stress is determined about the major and minor axes, respectively:
τbY = FY / AY
τbZ = FZ / AZ
The permissible shear stress is determined as:
When subjected to pure shear:
τab = 0.40 · Fy
When subjected to shear buckling:
τab = 0.70 · Vn · Avwhere
- Nominal Shear Strength as per Clause 22.214.171.124.(a)
= Vcr = τb · Av
- AY or AZ, whichever is appropriate, with reference to Clause 126.96.36.199.
Shear buckling must be checked when (d/ tw) > 67 · ϵw for webs without stiffener or (d/tw) > 67 · ϵw · √(Kv/5.35) for webs with stiffeners.where
- Clear Depth of Web between Flanges.
- Thickness of Web.
- √ ( 250 / Fy )
- Yield Strength of Web, specified using the FYLD parameter.
- Shear Buckling Coefficient:
= 5.35, when transverse stiffeners are provided only at supports.
= 4.0 + 5.35 / (c/d)2 for (c/d) < 1.0
= 5.35 + 4.0 / (c/d)2 for (c/d) ≥ 1.0
- Spacing of Transverse Stiffeners
- Poisson’s Ratio
- Shear Stress corresponding to Web-buckling:
= Fy / √3, when, λw ≤ 0.8
= ( 1 – 0.8 · (λw - 0.8) ) · (Fy / √3) when, 0.8 < λw < 1.2
= Fy / (√3 · λw 2 ) when, λw ≥ 1.2
- The Elastic Critical Shear Stress of the Web
τcr,e = (Kv · π2 · E) / (12 · (1 – μ2 ) · (d/tw)2 )where
- Non-dimensional Web Slenderness Ratio for Shear Buckling Stress.
- [Fy / (√3 · τcr,e)]1/2
Slender sections should be verified against shear buckling resistance if d/tw > 67 · ε for web without stiffeners or if it exceeds 67 · ε · √(Kv⁄5.35) for a web with stiffeners.
Design methods for resistance to shear buckling are described in clause 188.8.131.52 of IS:800-2007 code.
Vn = Vcrwhere