ON THE WEB CRIPPLING OF UN-STIFFENED COLD-FORMED CHANNELS

Web crippling of un-stiffened cold-formed channels, CFC, is rather complex due to many factors such as: high stress gradients at applied loads, web buckling, and local web yielding. The analysis of CFC subjected to concentrated loads was conducted herein by the finite element method incorporating geometric and material non-linearities. Unlike current design rules that underestimated test results by more than 35%, the numerical solution compared well with test results. The analysis conducted herein revealed that web crippling capacity was essentially governed by local web yielding. However, web buckling governed the behavior at some cases when the two flanges were loaded and/or when the inside bend radius was reduced and web slenderness was increased. On the other hand, the web capacity for end loading cases was less than that for interior loading cases by 50% on average, whereas loading two flanges reduced the web capacity by 8% compared to loading one flange. A new set of design rules for web crippling of CFC was established to provide a better estimation for numerical results compared to current design rules.