Experimental and numerical study on shear behavior of ultrahigh-performance concrete rubber-sleeved stud connectors in composite structures

Ultrahigh-performance concrete (UHPC) has been widely used for field-cast connections of steel–concrete composite structures to accelerate bridge construction. This paper proposed a UHPC rubber-sleeved stud connector, composed of the ordinary stud (OS) connector, rubber sleeve, and infilling UHPC, which could enhance the deformation ability of composite structures. Push-out tests and numerical simulations were carried out to study the behavior. The UHPC rubber-sleeved stud connector had a greater peak and ultimate slip than the OS connector, while the ultimate capacity was similar. The validated FE models were used for parametric analysis to determine the impact of several variables on the performance of UHPC rubber-sleeved stud connectors. Increasing the rubber sleeve's height and thickness could remarkably reduce the stiffness while little influence on the shear strength. The stud diameter had a beneficial impact on the stiffness and strength, but the UHPC compressive strength did not affect the ultimate capacity. Finally, a new formula was proposed to evaluate the shear stiffness and the average value of the calculated s to FE results was 1.003, which indicated the proposed formula could accurately predict the stiffness of UHPC rubber-sleeved stud connectors.