FEM Analysis of Web Crippling Phenomenon of Cold-Formed Steel Lipped C-Sections Subject to Two Flange Loading Cases

Cold formed steel lipped C-sections have been widely used in roof systems as purlins, decks as structural beams, and portal frames, etc., due to their superior properties such as higher strength and lighter weight compared to hot rolled steel. However, the webs of these sections are vulnerable to crippling phenomenon under localised loading when they are not generally strengthened by web stiffeners in cold-formed steel structures. This paper presents, in detail, the numerical studies using the finite element (FE) program ABAQUS to simulate the web crippling behaviour of cold-formed steel lipped C-section under two flange load cases. The FE models were developed using ABAQUS/Standard and their accuracy was validated by comparison with experimental results conducted by the authors in a separate experimental program. The section geometries and mechanical properties were based on the measured dimensions and the results of actual tensile coupon tests. Additionally, the initial geometry imperfections were also investigated in this study, and they were proven to have no or little effect on the ultimate strengths and can therefore be neglected. Detailed mesh sizes, contact definitions, interaction properties, boundary conditions and loading cases were considered for the FE models. Good agreement was achieved between the experimental and FE results. The reliable and calibrated FE models in this study will be used for a parametric study to extend data ranges without the need to conduct physical testing in the future research works.