Tests of Cold-Formed Steel T-Joints with Semi-Oval Hollow Section Chord

This paper presents a test campaign concerning the structural behavior of cold-formed steel T-joints with semi-oval hollow section (SOHS) chord. Three different sizes of SOHS and nine different sizes of rectangular hollow sections (RHS) or square hollow sections (SHS) were employed as chord and brace members, respectively, to fabricate the T-joint specimens. Robotic gas metal arc welding was adopted to connect the RHS/SHS brace to the flat flange of SOHS chord. The width ratio between brace and chord (β) ranged from 0.29 to 0.96. The brace-to-chord thickness ratio (τ) ranged from 0.46 to 0.72, and the chord width-to-thickness ratio (2γ) ranged from 10.3 to 13.9. A total of 29 T-joint specimens were tested with the chord simply supported and the brace axially compressed. The joint failure strengths, load-deformation histories, and failure characteristics of cold-formed steel T-joints with a SOHS chord are presented and discussed. The behavior of T-joints with a SOHS chord resembled that of RHS/SHS T-joints because the brace was connected to the SOHS chord at the flat flange. The feasibility of the design provisions in current standards initially developed for RHS T-joints was examined. The comparisons demonstrate that the strength predictions by the current standards are quite conservative for T-joints with cold-formed steel SOHS chord. The possible reasons for conservatism in design strength predictions are analyzed and discussed.