Numerical modelling of apex connections in cold-formed steel gable frames

Abstract

Cold-formed steel (CFS) sections have gained acceptance as primary elements in steel frames due to their exceptionally high strength to weight ratio. The main purpose of this research is to study the behavior of the apex joint in portals frame when subjected to monotonic vertical load. Numerical models for apex connections are developed using a finite element program to study the behavior of the connection. The numerical model is first verified by comparing its results with available experimental and numerical results. After the verification, the effect of several parameters on the connection performance was investigated. The parameters included the effect of the connecting gusset thickness and length as well as the effect of the distance between bolts. Moment-rotation relationships for different CFS apex connection numerical models were analyzed. The numerical models showed that the most significant modes of failure were gusset plate or beam web buckling. Increasing the distance between the two connected sections decreased the connection moment capacity, whereas increasing the thickness of the connecting plate enhanced the moment capacity.