Shear strength design of cold-formed steel channel sections with web openings

Abstract

Cold-formed steel (CFS) members are increasingly used as the main loading-bearing elements in modern construction practice, due to the advantages such as high strength-to-weight ratio, and ease of transportation and assembly. Often, web openings are cut out of CFS elements to allow for services, plumbing, heating and electrical systems, which may result in considerable reductions in their shear strength. This study aims to investigate the behaviour and design of CFS channel members with web openings under shear loads. To this end, detailed Finite Element (FE) models of CFS back-to-back channel members were developed featuring material non-linearity and geometric imperfections, and validated against the results of experimental tests. The validated FE models were then employed to carry out a comprehensive parametric study to investigate the effects of opening size and shape (square and circular web openings), as well as cross-sectional web slenderness on the strength, stiffness, failure mechanism, and ductility of CFS elements under shear forces. The results demonstrated that the shear strength of the CFS members can be significantly affected, up to 88 % and 30 %, by the size of openings and web slenderness, respectively. It was also found that while the ductility ratio of the CFS elements can be improved by increasing the opening size, elements with lower web slenderness showed less ductile behaviour. Based on the results of the parametric study, a practical design equation was developed for the shear strength of CFS members with web openings, and the predictions were compared with those determined by the AISI and other existing methods. Finally, a reliability analysis was performed within the framework of the European design standard.