强震下隔震连续梁桥地震响应的温度效应研究

基于某三跨隔震连续梁桥，分析了环境温度、隔震支座初始位移及铅芯热效应对其地震响应的影响。首先，分析了隔震支座产生初始位移的机理。在此基础上，选取36条近断层地震动记录，分别采用考虑与不考虑铅芯热效应的隔震支座模型，对该隔震连续梁桥进行了不同环境温度条件下的非线性动力时程分析，得到结构关键部位的动力响应。结果表明:低温环境条件下，环境温度、初始位移、铅芯热共同作用效应会使得隔震连续梁桥结构地震峰值位移明显减小，支座、墩底峰值剪力显著增大，环境温度对隔震梁桥地震峰值响应起主导作用；当环境温度超过常温（20℃）时，由于环境温度引起隔震支座力学性能显著退化，环境温度、隔震支座初始位移、铅芯热效应的共同作用使得结构地震峰值位移显著增大，此时初始位移与铅芯热对隔震支座峰值位移、剪力、墩底剪力影响更为显著。由于部分近场地震动作用下的结构峰值位移显著增大，使得其峰值剪力呈现出增大趋势。

THERMAL EFFECTS ON RESPONSE OF SEISMIC ISOLATED BRIDGES SUBJECTED TO STRONG GROUND MOTIONS

Based on a three-span continuous seismic isolated bridge (SIB), the effects of ambient temperature, initial displacement and lead core heating (LCH) on the response of SIB were investigated. The mechanism of shrinkage-induced initial displacement of lead rubber bearings (LRBs) was analyzed. Subsequently, 36 near-fault seismic records, the deterioration and non-deterioration hysteretic models of LRBs were selected for this study. The time history analyses were conducted under different temperature conditions, and the dynamic responses of SIB were obtained. Results show that initial displacement, initial displacement and lead core heating had significant joint effects on the peak displacement of LRBs, which were significantly reduced under low temperature values. However, the peak shear force of LRBs and the base shear force of the piers increased significantly, and low temperatures played a more dominant role than other two factors. Due to the degradation of LRBs induced by temperature and lead core heating, the peak displacement of LRBs with the joint effects increased significantly when the ambient temperature was above 20℃. Herein the initial displacement and lead core heating had more dramatic effects on the response of SIBs than the initial displacement. The peak shear force under partly selected near-fault excitations increased greatly since the corresponding peak displacement significantly increased.