Tests, numerical simulations and design analyses of eccentrically-compressed cold-formed thin-walled steel equal-leg angle columns

To investigate the buckling behavior and design method of eccentrically compressed cold-formed thin-walled steel equal-leg angle(CFTWSELA) columns, an experimental study was conducted on 36 specimens with different cross-sections, slenderness ratios, and width-to-thickness ratios. The test results indicated that the load-carrying capacities of CFTWSELAs under eccentric compression were lower than those of CFTWSELAs under axial compression. For the same eccentricities, specimens loaded eccentrically toward the heel demonstrated higher capacities than specimens loaded eccentrically toward the toe. Specimens failed with interaction of local buckling and global flexural buckling about the minor axis. The finite element models were validated against the performed experiments and showed good agreement with experimental results. A subsequent parametric study using the validated finite element model revealed that the ultimate capacity decreases with the increasing of eccentricity. This effect was more pronounced for members with lower slenderness and higher width-to-thickness ratios. The comparison on load- carrying capacities between the predicted results and the test and finite element analysis results indicated that the Direct Strength Method (DSM) in North American Specification was unconservative and the Effective Width Method (EWM) in Chinese code was overly conservative. Consequently, the modified design formulas based on the DSM and EWM are proposed. The proposed methods provided reliable predictions compared against experimental and numerical data.