Strength and Behavior of Elastic Critical Distortional Buckling for Cold-Formed Channel Member Under Compression

Distortional buckling of channel members is a critical factor in steel structures composed of thin-walled members; however, existing models have limitations in accurately predicting this behavior. This study analyzes the distortional buckling behavior of channel members using an energy method. A nonconventional mechanical model and displacement functions are introduced to simulate distortional buckling behavior, highlighting the limitations of conventional models. An evaluation formula for the elastic distortional buckling strength is derived, directly reflecting the geometrical parameters of the channel member using the proposed mechanical model. Additionally, a design equation is formulated. The proposed evaluation formula and simplified design equation enable the precise determination of the elastic critical distortional buckling strength, including cases where distortional buckling is initiated by local buckling of the web, which previous evaluation formulas could not address. These methods enable continuous evaluation of distortional buckling in channel members. The proposed formula and design equation were verified against finite element analysis results, confirming their reliability and effectiveness. The developed model and equations offer improved accuracy over conventional approaches for predicting distortional buckling in channel members, demonstrating their reliability and applicability under diverse conditions.