Stress Analysis Of Steel-concrete Bonding Section Of Single-tower Railway Cable-stayed Bridge

The hybrid beam cable-stayed bridge has been widely used in bridge construction in recent years due to its reasonable force,good static and dynamic performance,practical and beautiful features.The main span generally adopts steel beams to increase the spanning capacity,while the side spans use concrete beams to balance the load in the span,which can make full use of the concrete compressive performance and the tensile properties of the steel beams.Concrete beam and steel beam meet at the main beam.And the stiffness is abruptly changed here,so the steel-concrete joint section becomes one of the key structures in the hybrid beam cable-stayed bridge.In this paper,the combination of the full bridge and the local finite element model of the combined section is used to study the steel-concrete joint section of the single-tower railway hybrid beam cable-stayed bridge.The main contents and conclusions are as follows:(1)Taking the Yuekou Hanjiang Bridge as the engineering background,the finite element model of the full-bridge three-dimensional linkage system was established and the construction stages were simulated.The internal forces and stress values of the combined sections under different construction stages were analyzed.It provides the basis for the subsequent calculation and optimized design.(2)The force characteristics of five different structural forms of steel-concrete joint segment are studied.Through comparative analysis,it is found that the contact area between concrete and steel box girder is larger,which is more conducive to the arrangement of shear connectors,and the connection of concrete and steel is more tight than the non-compartment joint section.There is a large change in the stress at the joint surface of the combined pressure plate joint section of the lattice chamber.The stiffness transition smoothness is not as good as other type,but it is convenient for construction and easy to control the construction quality.(3)The force characteristics of the solid model of steel-concrete joints are studied.,and the role of shear nails is considered.The results show that the steel-mixed section of the Yuekou Hanjiang Bridge is well stressed,the stiffness transition is smooth,and it has a certain stress reserve.The maximum stress of concrete and steel appears in the top area of the joint surface,and the stress changes near the joint surface are large.The prestressed steel strand has a great influence on the web and the bearing plate.Special attention should be paid in the finite element model research and experimental research.(4)The influence of parameter changes on the force of the joint is studied.The different finite element models of the combined section is established by changing the design parameters of the combined section for analysis and calculation.The results show that the thickness of the bearing plate,the thickness of the steel box girder and the length of the steel cell chamber will reduce the stress on the top and bottom plates of the steel box girder.The upper edge of the concrete is reduced and the lower edge is slightly increased.The thickness of the bearing plate is reasonable from 60 mm to 70 mm,while the thickness of the top and bottom of the steel box girder is reasonable from 28 mm to 33 mm.The increase of the thickness of the web will reduce the overall stress of the steel-mixed section.Increased concrete strength will take on more stress.The two rows of shearing nails near the joint surface have a large stress,and when they fail,the third row of shearing nails will bear a large stress.