Flexural performances of steel–concrete composite section of self-anchored suspension bridge: Experimental and theoretical research

This paper aims to clarify the flexural performance and the cracking load, the ultimate bearing capacity calculation theories of the steel–concrete composite section of the self-anchored suspension bridge. A refined local finite-element (FE) model of the steel–concrete composite section was built to evaluate the mechanical performance of key parts under three unfavourable load conditions. A test model of the steel–concrete composite section with a length × width × height of 7 m × 1.833 m × 1.2 m was fabricated according to the scale of 1: 3, and a four-point negative bending test was carried out. The test results show that the test model is in the elastic stage, and the residual displacement ratio is 0.7 % under the design load condition. Under the overload condition (2.3 times the design load), the experimental model is in the elastic–plastic stage, and the residual displacement ratio is 19 %. At the same time, the stress of each component still meets the requirements. Under the two conditions, the deformation angle of the composite section is small, and the stiffness transition is stable. The relative slip between the top steel plate and the concrete in the composite section is small (no more than 0.25 mm). The stress of the top steel plate and bottom steel plate of the composite section gradually decreases during the transfer from the steel stiffening beam to the concrete side. The bearing plate is the main bearer of the force transmission of the steel–concrete composite section, accounting for about 51.24 %, while the top steel plate, bottom steel plate and shear connectors share the remaining load. The steel–concrete composite section of the test model has reasonable force, smooth force transmission and good deformation coordination performance. In addition, the calculation methods of cracking load and ultimate bearing capacity of the prestressed steel–concrete composite section were proposed. The theoretically calculated value of the ultimate bearing capacity of the steel–concrete composite section is in good agreement with the FEA value, and the difference does not exceed 10 %.