Shear properties of perforated plate nesting-grouting connector in prefabricated steel-concrete composite beams

To overcome the challenges of cumbersome construction, complex assembly, and low efficiency associated with traditional shear connectors in prefabricated steel-concrete composite bridges, a perforated plate nesting-grouting connector (PPNG) embedded in ultra-high performance concrete (UHPC) is proposed. Push-out tests on 27 specimens and finite element analysis were performed to examine failure modes, load-slip behavior, horizontal separation, and key parameters affecting the connector's shear properties. Results demonstrate that, for equivalent shear section areas, the shear capacity, shear stiffness, and ductility coefficient of PPNG connectors are 1.21, 1.27, and 2.65 times those of stud connectors, respectively. The nesting mechanism enables a synergistic interaction between the bearing capacity of UHPC and the plastic deformation of the shear steel plate, resulting in a load-slip curve with a pronounced "yield platform" during the plastic phase. The thickness of the shear steel plate and the nesting distance are identified as critical parameters influencing both the shear properties and failure mode of the PPNG connector. Predictive formulas for shear stiffness and capacity are established to estimate the shear properties of the PPNG connector.