Investigation Into Determine The Reasonable Cable Forces For Prestressed Concrete Cable Stayed Bridge

It is a key problem to determine the reasonable cable forces in designing cable-stayed bridges, and the design of cable stayed bridge is usually started on determining a reasonable complete status of the structure. There are several methods to determine a reasonable completed status of prestressed concrete cable stayed bridge and each one have good and bad sides. On the basis of analyzing and generalizing the former researchers' achievements, the least bending energy method combined with stress balance method is adopted to determine the reasonable cable forces in the paper.The least bending energy method takes the bending energy as the objective function, and gets the reasonable cable forces by seeking the least bending energy. Compared with different parameter for the least bending enery method in the paper and get the more reasonable parameter for analyse.The cable forces obtained by using the method are uniform. But in the solving process, the area of towers, girders and cables is magnified artificially. The influence of pre-stress can't be exerted and the potential energy caused by cable is ignored, so cable forces in dense cable area are unreasonable. Using this method can only determine cable forces caused by dead loads, but can't by live loads. The stress balance method aims at the girders' reasonable moment, getting the cable forces by balancing the stress in girder's upper and lower margin. Using this method can consider the influence caused by dead loads and live loads meanwhile. But cable forces in dense cable area are unreasonable. The synthetic method takes the state determined by least bending energy as its initial state, which is the base to adjust cable forces. Then according to the girders' reasonable moment, cable forces are adjusted to get the reasonable forces. Using this method can make good use of the two methods, and the cable forces determined by this method are more reasonable than that of the two. In this Paper,Using synthetieally Minimum Bending Energy method and Stress Balance method together,the optimization model of cable force of dead load is established,and get the reasonable completed cable force for one real project. At last analysis about influence of deflection of cables for the project.