E5Single-angle compression members

The nominal compressive strength, $P_{n}$, of single-angle members shall be the lowest value based on the limit states of flexural buckling in accordance with Section E3 or Section E7, as applicable, or flexural-torsional buckling in accordance with Section E4. Flexural-torsional buckling need not be considered when $b / t \leq 0.71 \sqrt{E / F_{y}}$.

The effects of eccentricity on single-angle members are permitted to be neglected and the member evaluated as axially loaded using one of the effective slenderness ratios specified in Section E5(a) or E5(b), provided that the following requirements are met:

• (1) Members are loaded at the ends in compression through the same one leg.
• (2) Members are attached by welding or by connections with a minimum of two bolts.
• (3) There are no intermediate transverse loads.
• (4) $L_{c} / r$ as determined in this section does not exceed 200.
• (5) For unequal leg angles, the ratio of long leg width to short leg width is less than 1.7.

Single-angle members that do not meet these requirements or the requirements described in Section E5(a) or (b) shall be evaluated for combined axial load and flexure using the provisions of Chapter H.

• (a) For angles that are individual members or are web members of planar trusses with adjacent web members attached to the same side of the gusset plate or chord
• (1) For equal-leg angles or unequal-leg angles connected through the longer leg

(i) When≤80 ra

(E5-1)

L (ii) When >80 ra Lc-32+1.25 (E5-2) r ra

• (2) For unequal-leg angles connected through the shorter leg, $L_{c} / r$ from Equations E5-1 and E5-2 shall be increased by adding $4\left[\left(b_{l} / b_{s}\right)^{2}-1\right]$, but $L_{c} / r$ of the members shall not be taken as less than $0.95 L / r_{z}$.
• (b) For angles that are web members of box or space trusses with adjacent web members attached to the same side of the gusset plate or chord
• (1) For equal-leg angles or unequal-leg angles connected through the longer leg

(i) When $\frac{L}{r_{a}} \leq 75$

(E5-3)

(ii) When $\frac{L}{r_{a}}>75$

(E5-4)

• (2) For unequal-leg angles with leg length ratios less than 1.7 and connected through the shorter leg, $L_{c} / r$ from Equations E5-3 and E5-4 shall be increased by adding $6\left[\left(b_{l} / b_{s}\right)^{2}-1\right]$, but $L_{c} / r$ of the member shall not be taken as less than $0.82 L / r_{z}$.

where

• $L$ = length of member between work points at truss chord centerlines, in. (mm)
• Lc = effective length of the member for buckling about the minor axis, in. (mm)
• $b_{l}=$ length of longer leg of angle, in. (mm)
• $b_{s}=$ length of shorter leg of angle, in. (mm)
• $\begin{aligned} r_{a} & =\text { radius of gyration about the geometric axis parallel to the connected leg, } \\ & \text { in. (mm) }\end{aligned}$
• radius of gyration about the minor principal axis, in. (mm)