Local-distortional interactive behavior and design of cold-formed steel C-sections with & without slotted holes

Cold-formed thin-walled steel structures are widely utilized owing to their significant performance in energy saving, environmental protection, and efficient utilization. The thin-walled nature of the sections is prone to complicated structural instability behavior. This study aims to investigate the ultimate load-carrying capacity of cold-formed steel (CFS) columns with holes in the web under local-distortional interaction through experiments. Thirty-two axial compression tests were conducted on fixed-end lipped channel columns with and without slotted holes. The test results, including the failure behavior, load-displacement curves, and load-strain curves of the specimens, demonstrated that local-distortional interaction occurred. Moreover, the ultimate strengths of the specimens with and without holes were compared to explore the effect of slotted holes. The results show that the slotted holes provide a slightly detrimental influence on the load-carrying capacity and stiffness. Finally, the current Direct Strength Method (DSM) to predict the actual L-D interaction behavior of lipped channel columns (with and without slotted holes) was evaluated based on the test results. It was shown that the current DSM cannot accurately predict the load-carrying capacity of CFS perforated columns with small lip stiffener widths. Besides, the novel design criterion with the DSM-shaped expressions to identify the actual L-D interaction behavior was discussed, and an improved method was proposed for perforated specimens. •Experimental evidence of 32 C-sections (with & without slotted holes) experiencing local-distortional interaction.•Validation of opening holes effect on load-carrying capacity and buckling behavior of C-sections under compression.•Discussion on failure characteristics of C-sections with slotted holes affected by L-D interaction.•Evaluation on DSM with a proposed identification criterion for C-sections undergoing L-D interaction.