Experimental investigation on cold-formed steel elliptical hollow section T-joints

A test campaign on cold-formed steel elliptical hollow section T-joints with the chord simply supported and the brace axially compressed is described in this paper. Four different sizes of elliptical hollow sections with the section aspect ratio ranged from 1.65 to 3 were employed to fabricate the T-joint specimens. Thirty-one T-joint specimens with three different types of member orientations were considered. Robotic gas metal arc welding was adopted to fabricate the elliptical hollow section T-joint specimens. The width ratio between brace and chord (β) ranged from 0.29 to 1. The brace-to-chord thickness ratio (τ) ranged from 0.60 to 1.77 and the chord width-to-thickness ratio (2γ) ranged from 10.6 to 52.3. All the T-joint specimens were tested with the chord simply supported and the brace axially compressed. The load-carrying capacities, load-deformation responses and failure modes of the elliptical hollow section T-joints are presented and discussed. Since no codified design provision is available for elliptical hollow section T-joints investigated herein, the feasibility of the design provisions originally developed for tubular T-joints with conventional cross-sections (i.e. circular hollow section and rectangular hollow section) as specified in the CIDECT and Eurocode 3 as well as the design recommendations proposed for hot-rolled steel elliptical joints was examined. Comparison results indicate that the joint strength predictions via these design methods are quite conservative and scattered for cold-formed steel elliptical hollow section T-joints.