Cold-formed ferritic stainless steel unlipped channels with web perforations subject to web crippling under one-flange loadings

Abstract

Stainless steel channels are increasingly used in the construction industry as load-carrying members, in particular in situations where low maintenance and high corrosion resistance is required. Amongst all stainless steel materials, ferritic stainless steels are the most economically competitive, and so potentially have the widest application in the building industry. This paper considers the use of cold-formed ferritic stainless steel unlipped channels with web perforations subject to interior-one-flange and end-one-flange loading, the benefit of perforations being ease of service integration. A total of 288 results are presented, comprising 18 laboratory and 270 numerical results. The numerical analysis in this paper uses nonlinear quasi-static finite element analysis with an implicit integration scheme. An extensive parametric study is described to determine web crippling capacity reduction factors for different sizes of web perforations and cross-section dimensions. It is noted that no cold-formed stainless steel standard provides capacity reduction factors for any one-flange load case. The capacity reduction factors are first compared to reduction factors previously recommended for lipped cold-formed stainless steel channels. It is found that these existing equations are unreliable and unconservative for unlipped channels by as much as 16%. From both laboratory and finite element results, web crippling design equations are proposed for channels with perforations in the web under one-flange loadings; the proposed equations are shown to be reliable when compared against laboratory and numerical results.