ULTIMATE CAPACITY OF COLD-FORMED STEEL HOLLOW STUB COLUMNS WITH ELLIPTICAL PERFORATIONS

This paper details a part of an underpinning research program focusing on structural behaviour of cold-formed steel stub column having two opposite central elliptical perforations. The effect of aspect ratio of elliptical perforations, i.e., keeping the diameter of ellipse perpendicular to loading axis as constant, on the ultimate capacity of stub columns was explored by considering two square hollow sections (SHSs) - stocky and slender cross-sections. Accompanying material and geometrical non-linearity, validated finite element (FE) models were developed using commercial FE software Abaqus. From the FE analysis results, it was observed that as the perforation diameter of ellipse to the flat element face of SHS ratio increases from 0.3 to 0.9, a reduction in column capacity of similar to 2.43. 9.85 % for stocky sections as the aspect ratio (or perforation area) changes from 0.25 - 1.75, whereas an enhanced reduction of similar to 5.10. 17.29 % was seen for slender sections. It was also seen that the effect of smaller diameter to flat width ratio resulted in lower drop in ultimate capacity.