铁路简支梁桥减隔震支座设计参数的优化研究

运用结构最优化理论建立了考虑地震时车辆运行安全性的铁路简支梁桥减隔震体系优化设计模型,采用ANSYS中的一阶优化方法,在优化过程中考虑结构Rayleigh阻尼系数的变化对减隔震体系的影响及土和基础的相互作用,实现了对铅芯橡胶支座动力设计参数的优化设计.通过计算分析,得出了铅芯橡胶支座动力参数对桥梁地震响应的影响规律：在应用LRB对不同场地条件下的铁路简支梁桥进行减隔震设计时,屈服后刚度与屈服前刚度比α对结构地震响应有重要影响.因此,可以采用改变屈服后刚度与屈服前刚度比α的简化设计方法,满足桥梁地震响应的要求.为了提高系统的优化效率,在进行减隔震支座优化时,行车安全性的约束可以在优化过程外考虑,即在支座参数优化解确定后,再进行车辆地震输入谱密度强度SI值的验算.

Study on Optimization of the Design Parameter of Seismic Absorption and Isolation bearing for Railway Simple Supported Beam Bridges

In this paper, the optimal design model of the seismic absorption and isolation system for railway simple supported beam bridges considering the running safety of vehicles is established. The first order optimization method in ANSYS is used to realize the dynamic parameters optimal design of the lead core rubber bearing, and the variation influence of the structural Rayleigh damping coefficients on the absorption and isolation system and the interaction between soil and foundation are considered in the optimization process. Through calculation analysis, the influence rules of dynamic parameters of the lead-rubber bearing on bridge seismic responses are given, the ratio of the stiffness after yielding to the stiffness before yielding a has important effect on the structural seismic responses in the seismic isolation design by LRB for simple supported beam bridges located in different sites. Therefore, the requirements for seismic responses of bridges can be satisfied by the simplified method of changing the a values. In order to enhance the optimizing efficiency, the running safety can be considered out of the optimizing process. That is to say, the values of spectral intensity SI for the seismic input to the running vehicles can be checked after the optimal LRB parameters are determined.