6.4beam-column bracing

For bracing of beam-columns, the required strength and stiffness for the axial force shall be determined as specified in Section 6.2, and the required strength and stiffness for flexure shall be determined as specified in Section 6.3. The values so determined shall be combined as follows:

• (a) When panel bracing is used, the required strength shall be taken as the sum of the values determined using Equations A-6-1 and A-6-5, and the required stiffness shall be taken as the sum of the values determined using Equations A-6-2 and A-6-6.
• (b) When point bracing is used, the required strength shall be taken as the sum of the values determined using Equations A-6-3 and A-6-7, and the required stiffness shall be taken as the sum of the values determined using Equations A-6-4 and

A-6-8. In Equations A-6-4 and A-6-8, $L_{b r}$ for beam-columns shall be taken as the actual unbraced length; the provision in Sections 6.2.2 and 6.3.1b, that $L_{b r}$ need not be taken as less than the maximum permitted effective length based upon $P_{r}$ and $M_{r}$, shall not be applied.

• (c) When torsional bracing is provided for flexure in combination with panel or point bracing for the axial force, the required strength and stiffness shall be com- bined or distributed in a manner that is consistent with the resistance provided by the element(s) of the actual bracing details.
• (d) When the combined stress effect from axial force and flexure results in compression to both flanges, either lateral bracing shall be added to both flanges or both flanges shall be laterally restrained by a combination of lateral and torsional bracing.

User Note: For case (d), additional guidelines are provided in the Commentary.