Mechanical Properties Analysis And Optimum Design Of The Super-span Suspension Bridge With CFRP Cables

With the application study of the carbon fiber reinforced polymer (CFRP) in bridge structure, the superiority that CFRP is applied to super-span suspension bridge is increasingly highlighted for special attention to designer. However, there is none this kind of bridge completed both at home and abroad, and there is no detailed and exact construction size to use for reference in preliminary design stage, so it is necessary to make optimum design. Some influences of fundamental parameters on static and free vibration characteristics of suspension bridges with CFRP cables are analyzed comparatively, then optimum design of static characteristics by zero-order optimization method and first-order optimization method is carried out in this article to expect obtaining the reasonable construction size.Firstly, the mechanical characteristics of CFRP and the calculation theories of suspension bridges, including elastic theory, deflection theory and finite displacement theory are introduced systematically in this article, which provides theoretical basis for the analysis of static and dynamic characteristic of suspension bridges. Besides, the construction optimum design theory including its categories, general mathematics model and mathematics is also introduced.Secondly, the theoretic limitation span of continuous suspension bridges with CFRP cables or steel cables are compared. The performances of both bridges are calculated and analyzed comparatively by making use of ANSYS, when they are under dead load, vehicle load and temperature load separately. Then, the differences mechanical properties of them in these working conditions are arrived.Thirdly, the static and dynamic performances of the 2000m-span and three-span continuous suspension bridges with CFRP cables are compared by making use of the ANSYS Parametric Design Language (APDL) through changing different parameters. The influence of these parameters are analyzed.The main parameters include the size and the sag of main cable, the ratio of side span to middle span.Finally, the methodology and procedure of optimum design are detailed introduced, and the optimum design of static characteristics for suspension bridges making use of zero-order optimization method and first-order optimization method is carried out in this article. The static and dynamic characteristic of suspension bridges before and after optimum are analyzed comparatively, to provide a certain valuable conclusion to the optimum design of super-span suspension bridge.