Analysis of Cable-Stayed Bridge for APDL-Based Optimization

Abstract

Optimum design for a cable-stayed bridge structure is very complicated because of large number of design variables. Use of ANSYS parametric design language in optimizing such structure consumes little computational time. The finished dead state analysis for single pylon double cable plane cable-stayed bridge with 120m long is performed. Mechanics equivalent are developed for the main pylon with concrete-filled steel tube. Prestress girder finite element model is established also. The theory of minimum bending strain energy is used in deriving the objective function as the quadratic form of the post-tensioning cable forces. In addition, the maximum deflection of the pylon and the maximum stresses of the main girder are both implemented in the optimization model. Optimized cable forces are found by optimization. Calculated results show that after the optimization, the cable force slightly changes, yet the internal force state under dead load remarkably improves, the bending stress of girder as well as the deflection of pylon significantly decreases. All these variations are satisfied for the limit value of engineering code. The results obtained revealed that the method presented indeed leads to optimal structural performance for the cable-stayed bridge in particular, and might be a useful reference for the design of other similar bridges.