Experimental study and strength evaluation of axially loaded welded tubular joints with round-ended oval hollow sections

摘要

Considerable research progress has been made in the investigation of the structural performance of steel and composite members with round-ended oval hollow sections (ROHSs). However, few studies have focused on the joint behaviour of ROHSs, despite their advantages, i.e. high structural efficiency, excellent flow smoothness, and outstanding aesthetic appearance. This paper presents a series of experimental studies on thin-walled ROHS tubular joints, including seven T-joint and six K-joint specimens, under axial compression. The effects of key design parameters, such as the ratio of the brace diameter to the chord width (beta), gap distance (g), and orientations and angles between the ROHS chord and brace, on the joint performance were investigated. Then, detailed investigations of the failure patterns, ultimate strength, initial stiffness, strain responses, ductility indices, and strength feature indices of the ROHS tubular joints were performed. The failure modes identified via axial compression tests of thin-walled ROHS tubular joints were primarily chord face plastification, weld fracture, and chord local buckling. The ultimate strength and the initial stiffness of the thin-walled ROHS tubular joint were significantly affected by the orientation between the chord and the brace owing to the novel structural feature of the round-ended oval cross-section. Compared with the predicted strengths of the axially loaded circular and rectangular hollow section tubular joints, the ROHS tubular joint exhibited a higher compression resistance because of its reasonable intersecting scheme. Finally, an assessment method for predicting the axial compression resistance of the ROHS tubular joint was proposed on the basis of the equivalent method and existing design provisions (i.e. the CIDECT-2009, GB50017-2017, AISC360-16, and EN-1993-1-8 specifications).