The Research On Cable Replacement And Cable Force Optimization Of Extradosed Cable-Stayed Bridge

Since the 1970 s,cable-stayed bridges have been built at a rapid pace.Due to the insufficient protection technology of early cable-stayed bridges.After years of operation,cable rusting disease will inevitably appear on cable-stayed bridges,and many cable-stayed bridges at home and abroad are about to face or have faced the problem of cable replacement.As cablestayed bridges are often in the local traffic arteries,they bear heavy traffic pressure.Therefore,how to replace the cable without interrupting the traffic condition is an urgent problem to be solved.At the same time,after the cable replacement is completed,the alignment and the cable force(internal force)level differ significantly from the design index.Therefore,it becomes a complex problem to optimize the adjustment of the cable force under such circumstances.In this paper,based on a short tower cable-stayed bridge cable replacement project,with the help of finite element software,we focus on the determination of the cable replacement plan and the optimization of the cable force of the completed bridge during cable replacement,and carry out the following work:(1)Summarize the current status of research on cable replacement scheme and optimization calculation of cable force of cable-stayed bridges at home and abroad,and outline the theory of computation of cable force of cable-stayed bridges after cable replacement.(2)Design of cable replacement scheme for cable-stayed bridges.By comparing the main girder displacement,cable force increment,tower displacement,and cable replacement speed after cable replacement,the results show that the working condition of removing two cables simultaneously with the main tower as the center is the optimal cable replacement scheme.Based on this scheme,the effect of temporary load on cable replacement of cable-stayed bridge is analyzed,and it is determined that cable replacement can be carried out safely and orderly under the condition of no interruption of traffic.(3)According to the calculation method of the cable force after cable replacement,the zero displacement method,the minimum bending energy method,and the influence moment method are used to calculate the cable force after cable replacement.(4)A cable force optimization method is proposed based on the improved whale optimization algorithm.The Enhanced Whale Optimization Algorithm,integrated with Salp Swarm Algorithm(ESSAWOA),is an enhanced biological algorithm based on the Whale Optimization Algorithm(WOA),which combines some features of the Salp Swarm Algorithm(SSA)and is supplemented by the Lens Opposition-based Learning(LOBL)strategy.The optimization model and constraints of the method are discussed in detail.Through the calculation of engineering examples,compared with the traditional cable force optimization algorithm,the application of this method results in a more reasonable bridge alignment and force state.