Analysis Of Reasonable Completed Bridge State And Optimization Of Hybrid Girder Cable-Stayed Bridge With An Inclined Pylon

Based on the preliminary design of a hybrid girder cable-stayed bridge with an inclined pylon, its static performance and reasonable completed bridge state have been analyzed in this thesis. Full bridge finite element model was established with MIDAS/Civil software, to analyze the static performance of completed bridge state under such single actions and combined actions as moving load, temperature change, shrinkage and creep. ANSYS local solid model of fixed tower-beam-pier part was established to compare with the member model. The calculated result shows that the location of negative girder moment peak in member model has a certain deviation to the local solid model, and the value of negative girder moment peak in member model is 15% larger than that in local solid model. The high accuracy of combination structure method in FEM on the simulation of the prestressed reinforcement has been validated by an example. It provides a simple and effective method for prestressing beam element model in ANSYS.Combined with ANSYS first-order optimization method, the dead moment feasible field method and combination structure method in FEM, the completed state of the inclined pylon hybrid girder Cable-Stayed Bridge has been analyzed using step-by-step arithmetic for the reasonable finished dead state of the cable-stayed bridges. The bridge structure has been divided apart and the bending strain energy of each part has been set with different weight coefficient with certain purpose to form the object function. Using this object function, the preliminary bridge state and cable forces have been determined with ANSYS first-order optimization method and the reinforcement has been prestressed with combination structure method on the preliminary bridge state. Considering the action of live load, the dead moment feasible field of girder and tower has been calculated. The new object function modified by the dead moment feasible field has been formed to proceed the secondary optimization of cable forces and the final reasonable completed bridge state has been determined. Comparing with the preliminary design, the optimization effect of the final completed bridge state is remarkable.The influence of the different locations of steel-concrete composite segment and back-cable anchorage on mechanical performance has been analyzed. The reasonable selections of the locations of these significant structures have been discussed from aspects of completed state and operation state. The selection method proposed in this thesis provides preliminary reference and suggestions for the design and study of this kind of bridge.