Investigation of block shear tear-out failure in gusset-plate welded connections in structural steel hollow sections and very high strength tubes

Block shear tear-out (TO) failure commonly occurs in gusset-plate welded structural steel hollow section (SSHS) connections under tension when a short weld length is used. However, investigation of TO failures in such connections is still limited. Very high strength (VHS) tubes, with a nominal yield stress of 1350 MPa, are produced for automotive industries in Australia, and may be used in gusset-plate welded connections. This paper presents an investigation of block shear tear-out (TO) failure for gusset-plate welded connections in both VHS tubes and SSHS. Twenty-five gusset-plate welded connections in VHS tubes with various weld lengths were tested under tension. The existing design rules for TO failure were examined by comparing their strength predictions with the test results from the welded connections in VHS tubes, previous test results from connections in SSHS and a combination of welded VHS tubes and SSHS. It was found that the existing design rules are inadequate, and five possible modifications have been examined. A modification of the effective net area and failure stress definitions is proposed. For this design model, a first order, second moment (FOSM) reliability analysis is performed and a resistance (capacity) factor of 0.70 is derived.