Block shear failure in welded gusset plates under combined loading

Block shear failure in the base metal of welded steel connections is a potential failure mode affecting many steel structures. However, there are only a few studies on the block shear failure of welded connections under combined shear and axial loading. Combined loading is defined as a simultaneous loading parallel and perpendicular to the weld lines (or an inclined loading) in the plane of the connecting plate. In this research, a nonlinear finite element model is used to study the effect of connection geometry and weld group configuration on the block shear strength of welded connections under combined loading. In current design standards, the block shear failure planes are assumed to consist of shear and tension planes, parallel and perpendicular to the applied load, respectively. The results obtained indicate that for combined loading, inclined failure planes are possible and the state of stress in such planes is a combination of tensile and shear stresses, the extent of which is proportional to the angle of loading. The results are used to describe the behavior of block shear rupture planes in such cases. Finally, to provide a better estimate of block shear strength in welded connections subjected to combined loading, a new equation is proposed that considers the actual shape of displaced block. •Block shear limit state in welded connections under combined shear and axial loads is studied.•Nonlinear finite element analysis using damage modeling has been utilized to observe block shear failure paths.•Block shear strength and failure path under combined loading are evaluated.•Failure planes are in a state of combined stresses.•Equations to estimate the block shear strength under combined loading are presented.