Effective Shaping of Cold-Formed Thin-Walled Built-up Beams in Pure Bending

Cold-formed thin-walled beams with an open cross section are widely used in different branches of industry. They tend to buckle in a variety of modes, which can be described as local, distortional, lateral-torsional buckling and bending. In this paper, the investigation on built-up I-sections, formed by assembling the stiffened cold-formed channel sections, with or without edge stiffener is presented. Parametric studies are carried out for five different section geometries with 16 specimens, tested under two point loading, to identify factors affecting the flexural strength of stiffened cold-formed steel built-up sections. The section geometries are chosen such that all types of buckling modes are met with. Critical load obtained from experiments is compared with finite element analysis results. Finally, it discusses the suitability of the current design methods (American Iron and Steel Institute) and provides design recommendations for stiffened cold-formed built-up sections.