Mechanical behaviour of steel-concrete joint in hybrid girder cable-stayed bridge

A steel-concrete joint section test model was constructed based on a mixed-scale ratio of the Lancang River hybrid girder cable-stayed bridge in Jinghong City, Yunnan Province. The internal forces and test loading values during normal operations were determined using finite element analysis. The performance was analysed by determining the mechanical indicators at key positions during the loading process. A finite element model of the test girder section was established to analyse the force transmission mechanism of the studied steel-concrete joint section. The test results showed that the centroid of the section moved upward during force transfer from the concrete to the steel girder. The relative slippage at the steel-concrete interface resulted in local unloading and an uneven distribution of longitudinal stresses in the crosswise direction. In addition, the cooperative bearing of the steel-concrete joint girder was transformed to a single bearing of the concrete girder, leading to a monotonic variation of stresses in the web plate. The simulation results showed that the surface plate force-sharing ratio of the composite bridge was the highest. In addition, the force-sharing ratios under the axial force and bending moment scenarios were 57.65% and 78.91%, respectively, indicating that the investigated steel-concrete joint demonstrated good stiffness transition stability. Furthermore, four force transfer types were identified in the steel-concrete joints. The research outcomes provide a fundamental basis for the rational design of joint components applied in hybrid girder cable-stayed bridges.