采用铅芯隔震橡胶支座的连续梁桥地震能量反应分析

基于多自由度桥梁体系地震能量反应方程,以一座铅芯橡胶支座隔震连续梁桥为例,选取5条具有代表性的地震波利用有限元的方法对全桥进行非线性动力时程分析,研究地震动峰值加速度、支座铅芯屈服力和屈服后刚度对桥梁结构地震能量反应的影响。分析结果表明:地震动峰值加速度对桥梁结构地震能量反应的影响较大,但对支座耗能比及阻尼耗能比的影响较小;支座铅芯屈服力及屈服后刚度对桥梁结构地震能量反应的影响较大,铅芯屈服力及屈服后刚度越大,支座耗能比越小,阻尼耗能比越大,反之亦然。增大支座铅芯屈服力及屈服后刚度不利于支座的滞回耗能,因此,在保证强度及位移要求的前提下应尽量采用铅芯屈服力及屈服后刚度较低的铅芯隔震橡胶支座。

Analysis of Seismic Energy Response for Continuous Girder Bridge with Lead-Rubber Bearings for Seismic Isolation

Based on the seismic energy response equation of multi-degree of freedom bridge system,taking a continuous girder bridge with lead-rubber bearing for seismic isolation as an example,five representative seismic waves were selected to analyze the nonlinear dynamic time history of the whole bridge by using the finite element method,and the influences of the peak acceleration of ground motion,the yield force and post-yield stiffness of lead bearing on the seismic energy response of the bridge structure were studied.The analysis results show that the peak acceleration of ground motion has a great influence on the seismic energy response of bridge structure,but it has little influence on bearing energy consumption ratio and damping dissipation energy ratio.The yield force and post-yield stiffness of lead bearing have a great influence on the seismic energy response of bridge structure.The larger the yield force and postyield stiffness of lead bearing,the smaller the bearing energy dissipation ratio,the larger the damping energy dissipation ratio and vice versa.Increasing the yield force and post-yield stiffness of lead bearing is not conducive to hysteretic energy dissipation of lead core bearing.Therefore,on the premise of ensuring the strength and displacement requirements,the lead-rubber bearing for seismic isolation with low yield force and post-yield stiffness should be used as far as possible.