Post-buckling properties of cold-formed steel thin-walled C-sections with improved-flanges of flexural rigidity

The impact of reduced and stiffened flanges on local buckling prevention and steel material efficiency was investigated by comparing the performance of cold-formed thin-walled C-sections featuring reduced and stiffened flanges (improved flexural rigidity) to those featuring plain plate flanges. This research investigated the post-buckling properties of cold-formed thin-walled steel C-sections with reduced-width or stiffened flanges under concentric compression. Initially, the effect of the half wavelength , V-shaped stiffener, web to flange ratio, and initial geometrical imperfections on load-bearing capacity and failure modes were studied. Axial compressive load vs. strain curves, axial compressive load vs. distortional displacement curves, and axial compressive load vs. shortening curves were experimentally measured and analyzed. In addition, a three-dimensional finite element analysis (FEA) model using ABAQUS program was established and validated. A parametric analysis employing the FEA model was performed. Moreover, theoretical analysis for the buckling modes and the performance of such sections was conducted based on the experimental results and the FEA results. Finally, a proposed formula and the current provisions from NAS 2016, AS/NZS 2018, and Chinese code JGJ227–2011 were evaluated based on these results. The results indicated that the several formulae were all in good agreement with the experimental results for such C-sections. • Experimental evidence of 18C-sections experiencing multi half-wavelength of distortional mode. • Validation of improving load-carrying capacity by enhancing flanges of flexural rigidity . • Discussion on post-buckling properties of C-sections with improved flanges. • Evaluation on a proposed formula for C-sections with improved flanges.