Strength of cold formed battened columns subjected to eccentric axial compressive force

Abstract

The strength of a battened beam-column composed of four slender cold formed angles is mainly governed by the local buckling of its elements as well as the overall buckling of the column. The local buckling mode is mainly affected by local slenderness ratio of one angle (between batten plates). Overall buckling mode is mainly affected by overall member slenderness ratio as well as angle legs width to thickness ratio. Members' failure modes occur by local buckling and yielding at short lengths, and by local flexural buckling at intermediate and flexural at long lengths. In the present study, the behavior of bi-axially loaded battened beam-columns composed of four equal cold formed slender angles is investigated. A nonlinear finite element model was developed to study the effect of the aforementioned factors on the ultimate capacity of members. Geometrical and material nonlinearities were considered in the model. A parametric study was performed on a group of battened beam-columns with variable angle legs having different outstanding leg width–thickness ratios, angle local slenderness ratios, and column overall slenderness ratios. The axial–bending interaction curves are presented for short, medium and long beam-columns having two different square cross sections. These interaction curves were compared with different code rules. These design rules have been shown to be reliable using reliability analysis.