Experimental and numerical investigation of angle-stiffened cold-formed steel lipped channels with web openings under ITF loading

This paper investigates the web crippling behaviour of cold-formed steel lipped channel sections with web openings subjected to concentrated loads. The effectiveness of angle stiffeners in enhancing web crippling strength under interior-two-flange loading is evaluated through experiments and validated finite element analysis. In this study, a total of 30 physical experiments were conducted to investigate the influence of angle stiffeners on the web crippling strength of CFS lipped channel beams with web openings under interior-two-flange (ITF) loading. Subsequently, a finite element (FE) model, which was developed and validated against the experimental results, was employed to perform an extensive parametric study comprising 490 simulations. The numerical analyses examined the effects of various parameters, including web opening size, bearing length, stiffener thickness, stiffener yield strength, distance from the web opening to the edge of the bearing plate and distance from the angle stiffener to the edge of the bearing plate. Overall, the findings demonstrate that angle stiffeners significantly enhance the web crippling strength of CFS lipped channel beams with web openings. Finally, based on the obtained results, design recommendations are proposed in the form of capacity modification factors to facilitate structural design practice.