Optimisation of cold-formed steel beams for best seismic performance in bolted moment connections

Typical thin-walled cold-formed steel (CFS) elements and connections used in portal frames are not generally suitable for moment-resisting high seismic regions due to their low ductility energy dissipation capacity inherited susceptibility local/global instabilities. This study aims improve the performance of CFS by developing a methodology obtain more efficient bolted moment using optimised beams with enhanced non-linear post-buckling behaviour. By taking into account material non-linearity geometrical imperfection effects, detailed Finite Element (FE) models typical connection is developed ABAQUS software, then validated based on experimental cyclic test results. Particle Swarm Optimisation (PSO) algorithm linked GMNIA FE analysis optimise either or ductility. To demonstrate efficiency method, five different beam cross-sectional shapes optimised, results compared standard channel section as benchmark. The relative dimensions cross-sections, inclination lip stiffeners, location triangular intermediate stiffeners selected main design variables. provide practical plate slenderness limit values defined Eurocode 3 (EC3) along range manufacturing limitations imposed constraints optimisation process. It shown that, given width thickness, proposed framework considerable (up 195%) improvement connections.