Pull-out performance of precast concrete deck–steel beam–connection concrete shear connection for prefabricated steel–concrete composite beams

<title>Abstract</title> Grouped stud connectors are commonly used in prefabricated steel–concrete composite beam bridges, but the reserved holes make it difficult to fabricate the concrete decks and weaken the integrity of the concrete decks. Thereby, a precast concrete deck–steel beam–connection concrete (PCSC) shear connection based on studs and ultra-high performance concrete (UHPC) was proposed in this study, and the experimental and numerical study on the pull-out performance of PCSC connection were carried out. The results indicated that the failure modes of PCSC connection were stud fracture and UHPC conical failure, and both were ductile. The critical length-to-diameter ratio of the studs leading to a transition in the failure mode is approximately 5.0. The load–displacement curves included elastic, elastic-plastic, yield, and failure stages. The length-to-diameter ratio of the studs and the tensile strength of the studs and UHPC are the primary factors affecting the failure mode and the pull-out capacity of PCSC connection. For UHPC conical failure, increasing the length-to-diameter ratio of the studs and decreasing the spacing of the connection enhanced both the pull-out capacity and stiffness. Lastly, based on the test results and the existing calculation formulas for the pull-out capacity of the stud connectors, the theoretical model and calculation formula for predicting the pull-out capacity of PCSC connection were proposed, considering the bond friction at the steel–UHPC interface. The computational method can provide practical guidance for engineering applications and structural design.