基于响应面法及粒子群算法的异形斜拉桥索力优化

Cable Force Optimization of Irregular Cable-Stayed Bridge Based on Response Surface Method and Particle Swarm Optimization Algorithm

为简化异形斜拉桥的索力优化过程,提出了采用响应面法与粒子群算法相结合的索力优化方法。该方法首先通过分析异形结构的受力特点确定优化目标,再利用响应面法将优化目标函数与成桥索力的关系显式化并构建响应面方程,最后结合粒子群算法根据响应面方程进行索力寻优。为验证该优化方法的有效性,以某异形斜拉桥为背景开展索力优化。基于该异形斜拉桥受力特点,以主梁的横梁两端最大剪力差为优化目标、以斜拉索成桥索力为优化变量、以斜拉桥成桥索力均匀性为约束条件,建立了索力优化目标函数进行索力优化。结果表明:优化后该异形斜拉桥主梁的横梁两端最大剪力差减小20.3%,主梁最大弯矩减小13.8%,南北侧边箱梁最大竖向位移差减小25.0%;全桥成桥索力及主梁弯矩均匀性均有所提升,主梁受力、线形更加合理。

A stay cable force optimization method that is developed on the basis of the response surface method and particle swarm algorithm is presented.First,the load bearing behavior of the irregular cable-stayed structure is analyzed to determine the optimization objective.Then,the response surface method is utilized to explicitly express the relationship between objective function and cable forces of completed bridge,afterwards,the response surface equation is derived.Finally,the particle swarm algorithm and response surface equation are employed to optimize the stay cable forces.To verify the effectiveness of the optimization method presented,a real irregular cable-stayed bridge is used as a case.Considering the load bearing behavior of the bridge,a stay cable force optimization objective function is established,where the maximum shear force difference between the two ends of the cross beam of the superstructure is reduced by 20.3%,the maximum bending moment of the superstructure is lessened by 13.8%and the maximum difference of shear forces at the two ends of the cross beam of the superstructure is taken as the optimization objective,the stay cable forces of completed bridge as the optimization variables and the cable force uniformity in completed bridge as the restraint.The results show that after optimization,the maximum vertical displacement difference between the south and north edge boxes of the irregular cable-stayed bridge is decreased by 25.0%.The uniformity of stay cable forces and superstructure bending moment after completion of the bridge has been improved,and the load bearing behavior and alignment of the superstructure are more efficient.