An investigation of the compressive strength of cold-formed steel built up channel sections

Abstract

Cold-formed steel members have been used extensively in low and midrise residential building construction. The usage of cold-formed steels as primary structural members has been increased due to its high load to weight ratio. Coldformed steel built-up sections are commonly used as compression elements to carry larger loads and over longer spans when a single individual section is insufficient. However, not much research has been done on built-up sections. This paper aims to investigate the compressive capacity of pin-ended cold-formed steel built-up lipped channel sections using finite element analysis (FEA). In the study, cold-formed steel built-up lipped channel consists of two identical C-channel sections oriented back to back with spacing between them and having a ratio of Ixx = Iyy which are connected by battens at top and at bottom throughout its lengths at regular intervals according to code based provisions. A non-linear finite element model is developed and verified against theoretical results. The thickness of the members is thin and hence they are susceptible to buckling, shell elements S4R are used in FE modeling. The theoretical analysis is based on effective width method and direct strength method and the results are generally conservative for cold-formed steel built-up channel sections.