考虑铅芯温度效应的橡胶支座参数影响分析

Comparative analysis of lead heating effects on lead rubber bearing behaviours

对铅芯橡胶支座试验中支座力学性能参数的不同确定方法进行比较,并考虑温度效应对支座铅芯屈服应力影响,采用修正双线性支座模型比较了考虑铅芯温度效应前后支座的累积塑性变形需求,在此基础上选用多条地震动实测记录分析铅芯温度效应对隔震支座力学性能和地震响应的影响,结果表明地震作用下铅芯随着塑性变形的累积和地震能量的耗散温度不断变化,三组不同场地波作用下铅芯屈服应力随着地震动输入的增大均呈现下降趋势,对于中硬土和基岩场地,铅芯屈服应力的国内规范取值较实际计算值偏小,导致支座位移响应的高估和支座剪力响应的低估,不能有效预测地震作用下隔震支座及结构真实地震响应。

A comparison between different approaches for evaluating lead rubber bearing(LRB) behaviours was presented by using horizontal shear tests.The cumulative plastic deformation demands on LRBs with and without considering the lead core heating effects were compared.The time histories of nonlinear responses were analysed to study the lead core heating effects on LRB behaviours and seismic performances,using three sets of ground motions classified according to their site categories.The results demonstrate that the lead yield stresses decrease apparently with the arising of seismic input level under the action of all the three motion sets,while the plastic deformation cumulation and lead core temperature are arising.It is also revealed that,for medium hard sites and rock sites,the values of lead core yield stress in the Chinese code are less than those obtained in the seismic analysis,which leads to the overestimate of bearing displacement responses and underestimate of shear force responses,and results in the inaccurate prediction of seismic responses.