依据能量平衡原理,建立隔震桥梁系统能量反应方程,将桥墩与铅芯橡胶支座串联,构建隔震桥梁能量反应的双线性分析模型。结合现行《铁路工程抗震规范》,合理选取40条强震记录作为地震输入,对不同周期的隔震桥梁系统进行非线性地震能量反应时程分析。结合铅芯橡胶支座本身的动力特性,给出具有统计意义的适用于I类场地的桥梁隔震设计地震输入总能量谱。提出以地震输入隔震桥梁系统的能量达到铅芯橡胶支座的极限耗能作为破坏准则、由地震输入总能量谱得到地震输入能量、隔震度作为隔震目标、隔震支座位移延性比作为限制条件的减隔震桥梁设计方法。
The energy response equations of the seismically isolated bridge system are established based on the energy equilibrium theory. Bilinear analysis model of the energy response of the seismically isolated bridge is constructed by series connecting the bridge piers and the lead rubber bearings. According to the applicable Code of Seismic Design for Railway Engineering, forty strong ground motion records are appro- priately selected as the seismic input and the nonlinear time history analyses for the seismic energy respon- ses of the bilinear SDOF seismically isolated bridge systems with different natural periods are carried out. Then according to the dynamic characteristics of the lead rubber bearing itself, the statistical seismic input energy spectra for the bridge seismic isolation design in I -type site are presented. Considering the seismic isolation bridge system input energy reaching to the utmost energy dissipation of the lead rubber bearing as the damage rule, and the seismic input energy acquired from seismic input energy spectra of this paper, and the seismic isolation degree taken as the isolation object as well as the ratio of displacement ductility of the isolation bearing taken as the restricted conditions, the design method of seismic isolation bridge is put forward.