Compression tests of thin-walled cold-formed steel columns with [formula omitted]-shaped sections and patterned perforations distributed along the length

Abstract

The North American design specification of AISI S100 (2016) incorporates the Direct Strength Method (DSM) to design cold-formed steel members with perforations under compression. However, the literature review showed that (i) the DSM has been used for nearly a decade, but the accuracy of the method is still not fully understood and (ii) although numerous studies concerning compression tests of cold-formed steel members with perforations have been conducted, only limited experimental data is accessible to the readers due to confidentiality issues. This study aimed at making efforts towards resolving the two issues. First, thin-walled roll-formed steel columns (count = 46) with three different Σ-shaped sections and six different lengths were tested under compression, where the columns were perforated and mostly tested with pinned ends. The column axial strengths and stiffnesses, failure modes, and structural responses under compression are reported in this paper. Then, the parameters required by the DSM for estimating the axial strengths of these columns were determined, and the results are also reported in this paper. Finally, the accuracy of the DSM was assessed with the tested axial strengths of the columns. It was found that the DSM could not accurately estimate the axial strengths of the columns rather these estimates were unconservative.