Lipped channel cold-formed steel columns under local-distortional buckling mode interaction

Abstract

Abstract The present research is aimed at verifying design rules for cold-formed steel (CFS) members under axial compression when local-distortional buckling modes (LD) is achieved. Sets of experimental results previously available were applied to calibrate a shell finite element model addressed to survey the structural behavior of CFS lipped channels under LD bucking interaction. A large range of distortional-local slenderness ratio was considered in order to obtain numerical results of LD interaction including strong and weak interaction conditions. Based on both experimental and numerical results, the nature of LD interaction was assessed and the column strength variation was observed according with the representative slenderness variables, λL, λD and RλDL, respectively local and distortional slenderness factors and distortional-local slenderness ratio λD/λL. The column strength variation was established based on the Winter-type equation, conceived to cover the complete range of LD interaction. The proposed solution follows the direct strength method concept, is easy to apply and accurate enough for the structural design of lipped CFS columns. Additional research is under way to include other CFS types in the proposed design approach.