F8Round HSS

AISC 360-22, Specification for Structural Steel Buildings

Last Updated 29 Oct 2026

Hover any section to copy its link or text, ask Copilot about it, or bookmark it.

This section applies to round HSS having $D / t$ ratios of less than $\frac{0.45 E}{F_{y}}$

The nominal flexural strength, $M_{n}$ , shall be the lower value obtained according to the limit states of yielding (plastic moment) and local buckling.

F8.1 Yielding

M_{n}=M_{p}=F_{y} Z

(F8-1)

F8.2 Local Buckling

(a) For compact sections, the limit state of flange local buckling does not apply.
(b) For noncompact sections

M_{n}=\left[\frac{0.021 E}{\left(\frac{D}{t}\right)}+F_{y}\right] S

(F8-2)

M_{n}=F_{c r} S

(F8-3)

where

$\begin{aligned} D & =\text { outside diameter of round HSS, in. (mm) } \\ F_{c r} & =\frac{0.33 E}{\left(\frac{D}{t}\right)}\end{aligned}$ (F8-4)

$t \quad$ = design wall thickness of HSS member, in. (mm)