Study On Ultimate Bearing Capacity Of Concrete Filled Steel Tubular Tied Arch Bridge

The CFST arch bridge is beautiful and externally stationary and it is widely used in the construction of urban bridge.With the increase of the design width of the bridge,the number of traffic lanes and the increase of the carrying capacity,the safety reserve has attracted much attention and the ultimate carrying capacity has become one of the focuses of the research.In this paper,the stability of the selected engineering example and the ultimate bearing capacity and the ultimate failure mode are studied in series.The influence of the nonlinear analysis method and the selected structural parameters on the ultimate bearing capacity is clarified.The main contents are as follows:(1)The constitutive relation of the material used in the CFST arch bridge is studied,and the detailed process of the finite element model is given,including the selection of the unit type,the constraint of the boundary condition,the application of the load and the connection between the parts;Based on the stress situation and structural characteristics of engineering examples,the difficulties and keypoints of ANSYS finite element model are analyzed.A simulation method of prestressing force is established by using beam element,and a nonlinear iterative model of unit combined load is established.(2)Firstly,the stability and safety factor of CFST arch bridge under line elastic analysis method is studied.The destabilization form is given and the process of solving the live load factor is given.Then,the influence of three nonlinear analysis methods,including material nonlinearity,geometric nonlinearity and double nonlinearity,and the calculation of ultimate bearing capacity of CFST arch bridge in bridge The necessity of using the double nonlinear analysis method to analyze the ultimate bearing capacity of CFST arch bridge is clarified.(3)Considering the effect of double nonlinearity,the ultimate bearing capacity of CFST arch bridge is analyzed by changing five related parameters,including arch rib concrete filling capacity,vector span ratio,bracing arrangement,load application method and concrete strength of main girder.The influence of the ultimate load capacity of CFST arch bridge under different parameters is studied by applying the equivalent deflection method of the load area,and the sensitive parameters of the ultimate bearing capacity of CFST arch bridge are clarified.(4)The ultimate failure mode of CFST arch bridge is studied,and the optimal design position of the cross-brace is given,and the importance of the four-point arch rib setting is emphasized.The area of partially filled concrete has a significant effect on the ultimate load carrying capacity of CFST arch bridge.The range of the span ratio is also significantly affected by the ultimate bearing capacity of CFST arch bridge.