SPATIAL NONLINEAR INTEGRATED OPTIMAL METHOD FOR STABLE SUSPENSION BRIDGE IN THREE STAGES

A stable suspension bridge is parametrically modeled in a three-dimensional space for its design difficulties and an integrated optimal method for the design is proposed, which combines the zero-order method and the first-order method. Considering the construction and nonlinearity of the bridge, the whole optimal process is divided into three stages in order to optimize the bridge step by step, with the mid-span deflection as the object function and the geometric as well as stress boundary conditions as the constrains. In the course of optimization some critical factors, such as the initial tension strains of the cables, the lengths of the suspenders and the height of the towers, are considered as design variables. On the other hand, the zero-order method, the first-order method and the presented integrated optimal method are compared, about the optimization effect to the bridge. After the full optimization, the stable suspension bridge arrives at a rational state pertinent to the force and deformations.