Cold-Formed Steel Check
Flexural buckling of a cold-formed member to AISI S100. The mechanics match hot-rolled steel, but the resistance factor is lower and the thin walls make local buckling the usual governing mode.
| Length (mm) | Capacity (kN) |
|---|---|
| 600 | 178.5 |
| 1200 | 178.5 |
| 1800 | 178.4 |
| 2400 | 178.4 |
| 3600 | 178.3 |
Fe = π²E/(KL/r)² · Euler.
Fn = 0.658^(λ²)·Fy for λ ≤ 1.5 · AISI S100 §E2.
φc·Fn·A, φc = 0.85 · Lower than the hot-rolled 0.90.
A clear path from inputs to results.
Flexural buckling of a cold-formed member to AISI S100. The mechanics match hot-rolled steel, but the resistance factor is lower and the thin walls make local buckling the usual governing mode.
How to use
- Set area (mm²).
- Set inertia (×10³ mm⁴).
- Set yield strength (mpa).
- Set unbraced length (mm).
- Read the headline metrics, then check the table for the detail.
The formula
Reference: AISI S100 §E2 with φc = 0.85.
Worked example
At the default inputs
- Area (mm²): 600; Inertia (×10³ mm⁴): 800; Yield strength (MPa): 350; Unbraced length (mm): 2400; Axial load (kN): 60
- 1
Design capacity: 178.4 kN · Critical stress Fe: 2.783e+5 MPa · Slenderness λ: 0.04 · Utilisation: 34%
Design capacity: 178.4 kN · Critical stress Fe: 2.783e+5 MPa · Slenderness λ: 0.04
Interpreting the result
The member carries 178.4 kN at λ 0.04.
Assumptions & limitations
- Centrally loaded member.
- No local or distortional buckling check.
Frequently asked questions
Why is φ lower than for hot-rolled?
Thin walls are more imperfection-sensitive, so AISI uses 0.85 against AISC’s 0.90.
What governs in practice?
Local buckling of the thin elements, which needs the effective-width method.
Methodology last reviewed 2026-10-22. Results are informational and not financial or engineering advice — see our disclaimer.