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.