Analysis Of Pushing Force And Horizontal Position Control Of A Thousand-metre Long Steel Truss Composite Girder Bridge

The push construction has the advantages of not affecting the original navigation and traffic of the bridge,without the need for brackets and large-scale mechanical equipment during construction,and a stable construction platform.It is widely used in the construction of steel bridges and prestressed concrete girder bridges.However,there is relatively little research on the top-elevation construction of the kilometer long steel-concrete composite girder bridge in China.Therefore,it is of great significance and application value to study the stress,stability and lateral position control of the bridge during the construction of the bridge.In this paper,a kilometer-long steel-concrete composite girder bridge is used as the engineering background.The MADIS/Civil is used to simulate the entire construction process of the guide girder and main girder and the main beam correction process.The ABAQUS simulation is used to analyze the lateral deflection of the girder to the lower chord.The effect of local forces on the overall nodes and the shifting beam is expected to provide theoretical references and technical support for the design and on-site construction of similar bridges.The main research results are as follows:(1)Through the simulation and analysis of the entire construction process,the force of each pier support,the internal force and stress of the girder and girder,and the key construction conditions were determined.Finally,the wind load under key construction conditions was analyzed.And the effect of temperature loading on the push structure.The results show that under the maximum cantilever state,the influence ofwind load on the shear force,torque,and moment of the structure is obvious;the minimum axial force,the maximum and minimum torque,and the maximum and minimum bending of the top surface heating on the structure Moment has the most significant effect.(2)The overall stability of the pushing structure in the construction process was analyzed by simulating the whole process of pushing construction.According to the first-order instability mode of linear buckling,the linear buckling eigenvalues ??and the nonlinear analysis critical load coefficients are compared with the relevant specifications,and the components that are likely to lose stability during the launch process are determined.At the same time,according to the relevant specifications,the overall stability of the component is calculated,and it is found that there is a deficiency in the stability and safety reserve of the longitudinal linking tie bar in the launching process,and then an optimization scheme is proposed,and the effectiveness of the scheme is verified.(3)The result of linear analysis shows that when the guide beam is about to reach Pier 9#,the deflection displacement at the front end of the guide beam reaches the maximum,and the guide beam can be successfully applied to the pier;the proposed optimization scheme can be applied to the vertical and horizontal directions of the maximum cantilever section.Significant improvement in displacement;in the process of pushing over each bridge span,the maximum vertical displacement of each span of the span of the bridge occurs when the guide beam is on the pier;the temperature rise of the top face is along the direction of the maximum cantilever section.And the lateral displacement has a great influence,especially the displacement along the bridge should cause the construction unit to pay enough attention.(4)Using ABAQUS to simulate the influence of the lateral deflection of the beam on the local force of the whole joint of the shifting beam and the lower chord,it is concluded that the lateral deflection of the beam has a greater influence on the local force of the shifting beam,and The bottom plate and the diaphragm of the joint have less influence.When the offset is 100 mm,the minimum third principal stress of the slide beam changes from-164.7MPa to-181.4MPa,an increase of 10.1%.(5)MADIS/Civil was used to simulate the lateral deflection of the main girder.Based on the variation law of the maximum tension and compression stress of the steel girder with different rectification amount,the reasonable correction range of the jack and the correcting force corresponding to different correction amount were given.Provides a theoretical basis for horizontal deviation correction at the construction site.