Formulas: Unbraced Length

Formula 1

The intent of these equations is to establish a minimum rotation capacity, $R_{c a p} \geq 3$, where $R_{c a p}$ is defined as shown in Figure C-A-1.2.

Formula 2

Formula 3

Case (b $M_{mid} \leq (M_1 + M_2/2$: When the mid-span moment ($L_b/2$ is less than or equal to the average of the end moments, the equivalent linear diagram directly connects the end moments $M'_1$ and $M_2$.

Formula 4

Case (c $M_{mid} > (M_1 + M_2/2$: When the mid-span moment exceeds the average of the end moments, the equivalent linear diagram is a sloped line passing through $M_{mid}$ at $L_b/2$, defining new effective end moments $M'_1$ and $M_2$.

Found in

• DESIGN BY INELASTIC ANALYSIS