Behaviour and strength of bolted connections failing in shear

Abstract

This paper investigates the behaviour and strength of structural steel bolted connections whose failure modes involve shear yielding and/or fracture. Such failure modes include the shear-out (or tearout) and the block shear failure modes. The use of shear failure planes corresponding to the bolt diameter is shown to result in significant overestimations of the ultimate capacities for bolted connections with reduced or no hole clearance. In contrast, the use of the effective (or active) shear planes are consistently accurate for the specimens with standard, oversize or no clearance bolt holes. The paper points out that the location of fracture initiation can be easily misidentified by a superficial inspection of the deformed and fractured state of the bolt hole. The paper also explains that the ultimate shear-out capacity of a steel bolted connection can be reached without fracture due to geometric changes downstream of the bolt, provided the reduction in resistance is not offset by strain hardening. The explanation is demonstrated through a finite element analysis that does not simulate fracture, but is able to accurately determine the ultimate shear-out capacity of a high-strength steel specimen tested by independent researchers.