Resistance of built-up cold-formed steel channel columns filled with concrete

Abstract

Cold-formed steel (CFS) channel infilled with concrete could increase its ability and stiffness by avoiding failure due to local buckling. Besides, the built-up bolted CFS channel column could serve as permanent formwork, decreased waste material and yet increase economical construction. This study aims to investigate the strength of built-up CFS channel columns infilled with concrete. Two CFS channel sections are situated face to face, connected and strengthen by using M10 bolts and nuts. Then, the 900 mm built-up column is filled with normal concrete of grade C30. Six samples with different end and central bolt spacing were tested. Material properties of CFS and concrete, and the mechanical properties of bolts are also investigated. From the result, the column with concrete on shortest end bolt spacing gave highest ultimate load and reported 68 – 78 % different when compared to similar column without concrete infilled. The failure mode of the column is global buckling and supports yielding, and the concrete is failed due to cracking and breaking. Equation of the relationship between bolt spacing either at the end or central and ultimate load is established.