Flexural and shear performance of prefabricated steel-concrete composite beams with keyed epoxied joints

Prefabricated steel-concrete composite (PSCC) beams with epoxied-joint concrete slabs exhibit superior prefabrication efficiency compared to conventional steel-concrete composite (SCC) beams with wet-joint concrete slabs. To investigate the flexural and shear performance of PSCC beams with epoxied joints, four-point bending tests were conducted on one conventional SCC beam and three PSCC beams with linear, stepped, and keyed epoxied joints, respectively. Key flexural behaviors, including vertical load, deflection, mid-span section strain, and interface slip, were examined. Subsequently, a full-scale three-dimensional nonlinear finite element simulation model was developed and its accuracy and reliability were validated against experimental results. Finally, extensive parametric studies were conducted to elucidate the effects of key-tooth depth, key-tooth height, loading location, and beam spacing on the shear performance of keyed epoxied joints in PSCC beams, along with a parametric sensitivity analysis. The results show that the PSCC beams with keyed epoxied joints exhibit high flexural capacity and ductility, comparable to SCC beams and superior to PSCC beams with linear or stepped epoxied joints. As the depth-to-height ratio approaches 0.5, the load location shifts closer to the steel beam, or the steel beam spacing decreases, the ultimate bearing capacity of the keyed epoxied joint increases. Load location and steel beam spacing significantly influence the shear performance and transverse shear force distribution of the keyed epoxied joint, which should be considered in practical design. The conclusions confirm the feasibility of PSCC beams with keyed epoxied joints and provide a theoretical basis for their wider application.