The confirmation of the collapse shape (buckling mode) of H-shaped beam is significant for limit state design. In the case affected by lateral torsional buckling, the general slenderness ratio is used as measure. In this study, the approximation of the general width-thickness ratio (as measure in the case of local buckling) based on the same concept as general slenderness ratio is presented. This approximation is produced by buckling analysis using the finite element method. And the varidity of classifying buckling mode based on the comparison between these above ratios is investigated. Futhermore, the presented bracing method (control of the collapse mechanism considering the above matter) is discribed. The control of collapse mechanism is made to be possible by the presented bracing attachment.
