Force-Transfer Mechanism Analysis of Steel–Concrete Joints in Railway Hybrid Girder Cable-Stayed Bridges

The force-transfer mechanism of a steel–concrete joint (SCJ) in a railway hybrid girder cable-stayed bridge was analysed using model tests and nonlinear finite element analysis (FEA), and the influence of the main design parameters on the load transmission performance was determined. The FEA results were in good agreement with the test results. The SCJ behaved linearly up to even under 2.0 times the design load, and the safety factors of the concrete and steel were not less than 2.02 and 2.55, respectively. The SCJ exhibited excellent deformation performance. Approximately 33.0% of the axial force was transferred from the steel girder to the concrete girder through the rear bearing plate (RBP), indicating that the RBP played an important role in force transfer. The force transmission efficiency of the steel cabin segment was approximately 2.0 times greater than that of the insert segment. The relative slip distribution along the bridge was saddle-shaped with large ends and a small middle. The uneven coefficients of the force shared by the PBL connectors and shear studs were 0.45–4.17 and 0.17–3.15, respectively. The deformation of the RBP was more complex than that of the front bearing plate (FBP), and the perforated plates, longitudinal prestressed tendons and webs strongly influenced the deformation distribution of the RBP. A parameter analysis revealed that the shorter the SCJ was, the greater the force transferred by the bearing plates and the greater the shear force shared by the shear connectors were. The greater the height of the steel cabin was, the greater the proportion of axial force transmitted by both the FBP and RBP was. Decreasing the stiffness of the PBL connectors and shear studs increased the relative slip considerably.