Tests of cold-formed steel built-up sections with web holes subjected to web crippling

This paper presents an experimental study on web crippling behaviour of cold-formed steel built-up Isections with circular web holes. The built-up sections were formed by connecting two identical unlipped channels with self-tapping screws. The web hole was located at mid-height of the web and directly beneath the bearing plates. Web crippling tests were conducted on 6 built-up sections without web holes and 19 built-up sections with perforated web under End-Two-Flange and Interior-Two-Flange loading conditions. The web crippling strengths, failure modes and load-displacement curves were reported. The experimental ultimate strengths for specimens without web holes were compared to the nominal strengths predicted from North American Specification, Australian/New Zealand Standard and European Code for cold-formed steel structures. It should be mentioned that the existing international design codes do not have explicit design formula to predict the web crippling strength of cold-formed steel built-up sections with perforated web. Therefore, the test strengths of specimens with perforated web were compared with the strengths derived from the design equations proposed in the literature. It is shown that the design strengths predicted from current design specifications are either conservative or unconservative for the specimens without web holes, while the design equations in the literature are generally unconservative for the specimens with perforated web.