Formulas: Lateral-Torsional Buckling

Formula 1

(b) For rectangular bars with $\frac{0.08 E}{F_{y}}<\frac{L_{b} d}{t^{2}} \leq \frac{1.9 E}{F_{y}}$ bent about their major axis

\frac{0.08 E}{F_{y}}<\frac{L_{b} d}{t^{2}} \leq \frac{1.9 E}{F_{y}}

Equation F11-3

M_{n}=C_{b}\left[1.52-0.274\left(\frac{L_{b} d}{t^{2}}\right) \frac{F_{y}}{E}\right] M_{y} \leq M_{p}

where

$L_{b}=$ length between points that are either braced against lateral displacement of the compression region, or between points braced to prevent twist of the cross section, in. (mm)

Formula 3

\frac{L_{b} d}{t^{2}}>\frac{1.9 E}{F_{y}}

Equation F11-4

M_{n}=F_{c r} S_{x} \leq M_{p}

Equation F11-5

F_{c r}=\frac{1.9 E C_{b}}{\frac{L_{b} d}{t^{2}}}

Found in

RECTANGULAR BARS AND ROUNDS