Shear performance of prefabricated steel– <scp>UHPC</scp> composite connections with bolt connectors

Abstract Steel–concrete composite beams have been extensively applied in the bridge engineering industry, owing to their advantages of light deadweight and fast construction speed. The development of prefabrication, lightweight, and high performance of steel–concrete composite beams has highlighted an urgent requirement for a shear connector suitable for prefabricated steel‐ultra‐high performance concrete (UHPC) composite beams. Therefore, a new demountable high‐strength bolt connector (DHSBC) was proposed and designed for utilization in prefabricated steel–UHPC composite connections. This composite connection consists of an UHPC slab with embedded nuts, H‐shaped steel columns with pre‐drilled bolt holes, and high‐strength bolts. The push‐out tests were conducted on eight DHSBC specimens, with particular attention paid to the design parameters for the specimens, involving bolt diameter, bolt embedment depth, and nut materials. The failure modes, capability, and strain development of specimens under shear loading were analyzed in detail. Subsequently, a finite element model (FEM) was generated and verified with experimental results. The validated FEM was further employed to investigate the influence of some factors. Ultimately, an analytical formula for the load–slip curve of specimens was suggested by fitting of numerical results, alongside the derivation of the stiffness–slip curves. The applicability of the proposed formula was validated through a comparison with experimental results. The research findings provide a reference basis for the design of shear connectors in prefabricated steel‐UHPC composite beams, and offer valuable insights to enhance their engineering applications.