Leaning Arch Is Reasonable As The Bridge Cable Force And The Cable Forces To Determine The Construction Phase

The stress and the structure of double X-arch bridge is complex, with the obvious spatial effect, especially the existence of stay cable that redistributes the load among girder, the main arch and inclined arch, the difficulty of cable force calculation and optimization is increase. The key point of double X-arch bridge design and construction lies in how to confirm the reasonable cable force of finished state and that during construction, it can make the structure stress properly. This dissertation sets the background on a design of double X-arch bridge in Hunan to have a systematic analysis on reasonable cable force of finished state and that during construction. The main research and achievements include:1. For double X-arch bridge has obvious spatial effect, with the tool of influence matrix, the dissertation proposes a method, using least in-plane and out-plane bending strain energy as object function, to determine the reasonable cable force of finished state. The results show that the principle that can optimize in-plane stress by considering out-plane stress and enables a proper distribution of energy among components.2. Sets the background on a design of double X-arch bridge in Hunan, using least in-plane and out-plane bending strain energy as object function, study the constrained and unconstrained optimization method for determining cable tension in reasonable finished state. By a comparative analysis among three usual method for determining reasonable finished state. The applicability of methods which proposed in the dissertation has been verified.3. It consume a lot of work to modify influence matrix when using forward-iteration method to determining the reasonable cable force of construction state. A method modify influence matrix with a trestle-off factor and two system influence matrix is introduced, which can save the work and the computational efficiency is greatly increased. The results proves that, when modify the cable force during forward-iteration calculation,the iteration is more effictive if the cable force is modified by means of calculating seperately the partitioned matrixes of the main calbes and the stay cables.