Experimental study and theoretical analysis of the shear resistance performance of high-strength bolt connectors in prefabricated steel-concrete composite beams

To achieve the full assembly and detachability of steel beams and concrete floor slabs, this study employed high-strength bolt connections in steel-concrete composite beams. Five push-out tests were designed to analyze the load-slip curves, shear stiffness, ductility coefficients, and detachable performance of the connections comprehensively. The results show that the failure of the steel–concrete composite beams starts from the shear yield of the bolt and the partial crushing of the concrete, and the final failure mode is bolt shear. The bolt diameter and concrete strength are the two major factors that determine the shear capacity of composite beams. The concrete strength is appropriately reduced, which is a novel result, and after the local pressure and cracking of the concrete, the contact area between the bolt and the concrete hole increases, and the bearing capacity and deformation increase. By defining the bolt strength and concrete strength, the bearing capacity ratio η is calculated, and the calculation formula of the shear bearing capacity and the η of the composite beam is established. The results of this paper provide an important theoretical reference for the design of the bolt shear capacity of composite beams and the possibility of a fully assembled and detachable structure.