Web crippling design of cold-formed ferritic stainless steel unlipped channels with fastened flanges under end-two-flange loading condition

In this paper, a combination of tests and non-linear finite element analyses is used to investigate the web crippling strength of cold-formed ferritic stainless steel unlipped channels with fastened flanges under the end-two-flange (ETF) loading condition; the cases of both unlipped channels with and without web holes are considered. The results of 27 web crippling tests are presented, with 9 tests conducted on unlipped channels without web holes and 18 tests conducted on unlipped channels with web holes. In the case of tests with web holes, the holes are located either centred or offset to the load and reaction plates. An extensive parametric study is undertaken, using quasi-static finite element analysis, to investigate the effects of web holes. The strengths obtained from reduction factor equations are first compared to strengths calculated from equations recently proposed for cold-formed stainless steel lipped channels. It is demonstrated that the strength reduction factor equations previously proposed for cold-formed stainless steel lipped channels can be unconservative for cold-formed ferritic stainless steel unlipped channels by up to 10%. The laboratory investigation also shows that, for the case of unlipped channels without web holes, the European Standard (EN 1993-1-4) and the American Society of Civil Engineers Specification (SEI/ASCE-8) are too conservative by 43% and 28%, respectively. From both laboratory and finite element results, web crippling design equations are proposed for both sections, with and without web holes.