What is the critical buckling stress Fcr per AISC 360-22?
Per AISC 360-22 Section E3, Fcr = [0.658^(Fy/Fe)] Fy when KL/r ≤ 4.71√(E/Fy), and Fcr = 0.877 Fe when KL/r exceeds this limit (elastic Euler buckling governs).
Design steel columns for axial compression including slenderness and buckling effects. Use for W-shape or HSS column capacity checks under axial load.
Design steel columns for axial compression including slenderness and buckling effects. Outputs: critical buckling stress Fcr, axial capacity φPn, slenderness ratio.
Governing Code Standard: AISC 360-22 Ch. E.
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Per AISC 360-22 Section E3, Fcr = [0.658^(Fy/Fe)] Fy when KL/r ≤ 4.71√(E/Fy), and Fcr = 0.877 Fe when KL/r exceeds this limit (elastic Euler buckling governs).
K accounts for end conditions: K = 0.5 for fixed-fixed, K = 0.7 for fixed-pinned, K = 1.0 for pinned-pinned, K = 2.0 for cantilever (fixed-free). Conservative values are used when end conditions are uncertain.
AISC 360-22 Section E2 recommends KL/r ≤ 200 for compression members as a practical limit, though no mandatory limit exists for primary structural members.
φPn = φc × Fcr × Ag, where φc = 0.9 for compression, Fcr is the critical buckling stress, and Ag is the gross cross-sectional area.
AISC 360-22 Table B4.1a classifies flanges and webs as compact, noncompact, or slender based on width-to-thickness ratios. Slender elements reduce the column capacity through local buckling.
AISC 360-22 §E — Compression member design
This calculation is for preliminary design verification only. All results must be independently verified by a licensed professional engineer before use in construction documents.