Design of Built-Up Cold-Formed Steel Columns According to the Direct Strength Method

The (DSM) direct strength method [1] is used in order to predict the axial compression capacity of innovative cross-section shapes for built-up columns from cold-formed steel (CFS) profiles. The proposed four composed shapes have been adapted in order to obtain members of increased strength-to-weight ratio. After excluding various buckling mechanisms from the columns response to compressive loads, highly stable members with reduced sensitivity to initial imperfections are obtained. DSM predictions are validated experimentally for the four built-up cross-sections types. The investigation shows that DSM could easily be extended towards composed members if provisions for members sensitive to global-distortional buckling interaction are included in the method. The good agreement with experiments also indicates that the proposed built-up assemblies are reliable and can be integrated into everyday construction practice.