Theoretical and experimental study on the critical load of cold-formed thin-walled complex rolled-edge channel steel columns

This study investigates the critical buckling load of cold-formed thin-walled complex rolled-edge channel steel (CF-TWCRC) columns under eccentric axial compression. An energy-based theoretical model incorporating torsion and warping effects was developed and validated experimentally using columns of varying heights (21–72 mm) and lengths (330–530 mm). Failure modes transitioned from flexural-torsional buckling (small sections) to local–global interaction (large sections) with increasing slenderness. Nonlinear finite element models (ABAQUS/S4R shells) accurately simulated complex buckling behaviours. Results show: (1) Theoretical predictions align with experiments (errors <10%) and simulations (errors <6.3%), confirming model reliability; (2) Load eccentricity significantly reduces buckling capacity by inducing compression-bending coupling; (3) Section height and member length critically govern failure modes and strength. The proposed model provides essential tools for safe CF-TWCRC column design under realistic eccentric loading.