Experimental investigation on post-flexural–torsional buckling strength of CFS compression members

Abstract

Recent studies have indicated that cold-formed steel (CFS) members could have strength above the global elastic flexural–torsional buckling (FTB) load. No test result demonstrating the post-buckling strength of channel compression members undergoing only FTB before failure is reported in the literature. Test results on a total of 25 CFS specimens, which included 19 channels (hat section, lipped channel, and plain channel) and 6 angles which experience only FTB under axial compression, carried out in this study, are presented. The interaction of other modes (flexural, local, and distortional) with FTB, which may reduce the ultimate strength of the member, was eliminated in this study by choosing the geometry of test specimens having elastic FTB load much smaller than the elastic buckling loads corresponding to other modes. The global buckling strength equations in the design standards and the modified equations reported in the literature are evaluated using the results generated in this study. The modified procedures proposed by Dinis et al. (2020), and Dinis and Camotim (2019) are found to be the most accurate for channel and angle compression members failing under FTB mode, respectively.