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. 22.214.171.124. The full cross-sectional area is considered as the shear area for a solid rod section.
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. 126.96.36.199(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 188.8.131.52.(a)
= Vcr = τb · Av
- AY or AZ, whichever is appropriate, with reference to Clause 184.108.40.206.
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 220.127.116.11 of IS:800-2007 code.
Vn = Vcrwhere