Design recommendation of cold-formed steel built-up sections under concentric and eccentric compression

Abstract

A parametric investigation and design proposal for the back-to-back built-up cold-formed steel (CFS) channel sections with V-stiffeners and Σ-stiffeners under concentric and eccentric loading are presented in this paper. A nonlinear finite element model considering the initial geometric imperfection was developed and validated against experimental results. A total of 594 simulations were conducted involving a variety of slenderness ratios, eccentric axis directions, eccentricity, screw spacing and number of longitudinal holes. Simulation results including the load-carrying capacity, failure modes, ultimate bearing capacity versus eccentricity relationships, and load versus lateral displacement relationships were discussed. The influence of several member parameters on the load-carrying capacity and buckling modes was analyzed. Additionally, the applicability of the design strengths calculated from Chinese standard GB50018–2002 and North American specifications AISI S100–16 was evaluated based on the preliminary experimental results and simulation results. It was shown that both methods are conservative. Finally, a proposed DSM-based interaction equation considering the relationship between P/Pnd and M/Mnd was proposed and evaluated.