scope:

The AISC interaction equation approach is a very convenient design tool and has been widely accepted as the basic design approach for beam-columns. This study has addressed itself to one special aspect of the interaction equation approach (lateral-torsional buckling failure mode) and resulted in a conclusion that for lateral-torsional buckling, a modification function to the bending stress ratio (fb/Fb), different from the AISC format, can provide improved designs on a more rational basis. For in-plane failure mode the present AISC interaction equation remains a very good approach.