Behaviour of Doubly Symmetric Built-Up Cold-Formed Steel Beams

Abstract

This article presents the study on the behaviour of doubly built-up cold-formed beams under flexure. The built-up sections are made by connecting two channel sections back to back which are attached by welding. A series of experiment tests were carried out on beam specimens having with lip and without lip sections, each with 200 mm depth and 240 mm depth respectively. The adopted thickness of beam section is 1.6 mm and 2 mm. The parameters involved in this study are effective width to thickness ratio and sections with and without lip. All the beams failed at local buckling at top flange due to lateral instability of the cold-formed steel structural members and then followed by lateral torsional buckling. The theoretical calculations are made as per IS: 801-1975 code, which is based on the working stress method. The analytical investigation of the built-up section is also carried out using FEM modelling software. All the specimens indicate nearly closer values to each other in theoretical, analytical and experimental study. From this study, it is concluded that doubly symmetric built-up cold-formed sections are preferred for higher load carrying capacity with less complicated buckling modes.