双层连续梁桥等效线性化方法隔震分析

为了在现行桥梁设计软件上进行连续梁桥的隔震分析,模拟铅芯橡胶隔震支座在地震、温度荷载作用下的非线性,研究了采用等效线性化方法进行桥梁隔震分析的步骤与精度。假设支座初始刚度,加载计算支座的相对位移,并得到支座水平刚度,经过反复迭代得到铅芯橡胶隔震支座的等效刚度。在此基础上将体系简化成线性系统按弹性方法进行计算,以安装了铅芯橡胶隔震支座的双层连续梁桥为例,分别计算等效模型和非线性模型在水平地震、均匀升温、横向风荷载和制动力作用下的响应,并讨论了等效线性化方法计算时的相关问题。与非线性分析结果比较,等效线性化法可以模拟水平地震和温度荷载作用下支座的非线性,结果满足桥梁工程的精度要求。隔震支座在横向风荷载和制动力荷载作用下一般不会屈服,使用第一刚度计算即可。

Analysis of Seismic Isolation of Double Deck Continuous Bridge Based on Equivalent Linear Method

To analyse seismic isolation of continuous bridge with leadrubber bearings(LRB) by commonly used bridge-design software and simulate the nonlinearity of LRB under seismic and temperature loads,the process and precision of equivalent linear method were studied.First,initial stiffness of the bearings was supposed,and the relative displacement was computed on the special load.Based on the relative displacement and the shearing force of bearings,horizontal stiffness was obtained.And then the equivalent linear stiffness was computed by iterative method.The nonlinear bridge was simplified to equivalent linear system by elasticity methods.Take a double deck bridge with LRB as an example,the reactions of equivalent linear model and nonlinear model under horizontal seism,uniform temperature increase,lateral wind loads and braking force,were calculated and analyzed respectively.The former is computed by elasticity statics methods and the latter is computed by nonlinear statics or dynamics methods.The forces and displacements of pier and girder were obtained by two of them.Meanwhile,a series of problems on equivalent linear method were discussed,such as the astringency of equivalent linear model and the system damping ratio.Compared with nonlinear model,equivalent linear model meets bridge engineering requirements,especially on seismic and temperature load.The LRB are usually not yielding on wind loads and braking force,and in that case,the first stiffness is suitable for bridge design.