FEM-based analysis of the local-plate/distortional mode interaction in cold-formed steel lipped channel columns

摘要

This paper reports the results of a numerical investigation concerning the elastic and elastic-plastic post-buckling behaviour of cold-formed steel lipped channel columns affected by local-plate/distortional buckling mode interaction. The results presented and discussed were obtained through analyses performed using the finite element code Abaqus and discretising the columns by means of fine 4-node shell element meshes. The columns analysed (ⅰ) are simply supported (end sections locally/globally pinned and free-to-warp), (ⅱ) have cross-section dimensions that ensure equal local-plate and distortional critical buckling stresses, thus maximising the local-plate/distortional mode interaction effects, and (ⅲ) contain critical-mode initial geometrical imperfections that exhibit different shapes but share the same combined amplitude. The numerical post-buckling results reported consist of (ⅰ) elastic and elastic-plastic non-linear equilibrium paths, (ⅱ) curves and figures describing how the column deformed configuration (expressed as a linear combination of its local-plate and distortional components) evolves along the elastic post-buckling equilibrium paths and (ⅲ) figures providing a clear visualisation of the (ⅲ_1) evolution of the elastic-plastic column deformed configurations, (ⅲ_2) the growth of the plastic strains and (ⅲ_3) failure mechanisms exhibited by a fairly large portion of the elastic-plastic columns that were analysed in this work.