DSM DESIGN OF COLD-FORMED STEEL COLUMNS AFFECTED BY LOCAL-DISTORTIONAL-GLOBAL INTERACTION REVISITED
Pedro B. Dinis and Dinar Camotim
CERIS, ICIST, DECivil, Instituto Superior Técnico, Universidade de Lisboa, Portugal
This work revisits the Direct Strength Method (DSM)-based prediction of the ultimate strength of cold-formed steel columns affected by local-distortional-global (L-D-G) mode interaction in the light of the recent findings concerning the global failure load prediction accuracy. After reporting the column failure load data previously collected, the paper presents the available DSM-based approaches to design columns against the above triple interactive failures and summarizes the past work of the authors on the design of those columns. Next, an overview of two proposed DSM-based column global strength design curves, developed to improve the failure load prediction quality provided by the current DSM global design curve for columns failing in flexural-torsional and flexural modes, is provided. Finally, the failure loads of the columns affected by L-D-G interaction are used to assess whether their predictions provided by the currently available DSM-based approaches are improved when adopting the novel column global design curves. Indeed, It is shown that the inclusion of these curves in the available DSM-based design approaches against L-G and D-G interactive failures improves the failure load prediction quality for lipped channel, hat, rack and zed-section columns under L-D-G interaction.
Cold-formed steel columns; Local-distortional-global interaction; Direct Strength Method (DSM) design; Novel DSM global strength curve; Failure load prediction quality