Research Projects

Web crippling of cold-formed steel (CFS) beams is a complex issue due to localized load. Design standards recommend empirical equation-based coefficients for web-crippling strength, which are often tedious and inaccurate. The direct strength method (DSM) has been extended to web-crippling strength, but it is often idealized as a stability problem due to the possibility of web buckling. The ultimate test load can be as high as two times of yield load, attributed to 'inelastic reserve' in the literature. However, this inelastic reserve is not possible for bending and compressive behavior, indicating fundamental flaws in DSM procedures. The hypothesis proposed in this study is that the effect of slenderness (or buckling) on web-crippling strength is insignificant. A preliminary numerical study showed that webs fail due to bending stress generated by the eccentricity of the load being much higher than the axial compressive stresses, making a DSM-based equation inappropriate. A preliminary theoretical explanation for this hypothesis is also presented in the proposal. The overall objective is to study the web-crippling behavior of CFS beams using experimental and numerical results and propose a simple and more accurate design equation. The investigation will be based on the experimental and numerical study of specimens with and without web opening for different cross-sections under different loading and fastening conditions.