Behaviour of large-diameter high-strength bolted shear connections for prefabricated composite beams

This paper presents an experimental investigation into the structural behaviour of a new proposed shear connection incorporating high-strength large-diameter steel bolts in conjunction with steel fibre reinforced concrete blocks. A detailed account of fourteen large-scale push-out tests is provided with the aim of examining and quantifying the full deformational characteristics of these shear connections. The results include the loadslippage responses, shear resistances, and failure modes for the various specimens. It is shown that the proposed connection configuration is suitable for prefabricated composite beams in highway bridges and can be detailed to provide high stiffness over 1500 kN/mm, large shear resistance exceeding 1000 kN, and slippage at failure greater than 6.0 mm. The proposed connection can also be easily assembled on site and provides significant resistance against pull-out forces. Based on the experimental results, complementary design procedures are proposed to enable a prediction of the shear resistance of the connections. A simplified load-slippage relationship for the shear connections is also suggested and shown to represent closely the full deformation characteristics. Overall, the proposed shear connection configuration is shown to offer considerable stiffness, resistance, and ductility, and can be readily installed on site for joining steel beams and precast slabs in combination with high performance in-situ concrete. This connection form contributes to an enabling construction technology for promoting effective prefabrication of composite bridge structures.