基于能量平衡原理,建立连续梁桥能量反应方程。采用有限元分析软件SAP2000,对4条典型地震波双向激励下的非隔震与铅芯橡胶支座隔震连续梁桥的地震能量反应进行分析。结果表明:铅芯橡胶支座隔震连续梁桥的绝大部分地震输入能(80%左右)被铅芯橡胶支座的滞回耗能所消耗,铅芯橡胶支座起到了减少结构非弹性变形、保护主体结构的作用;铅芯橡胶支座的构造对其隔震的连续桥梁的地震能量反应影响较大,较大的铅芯直径和刚度比会导致铅芯橡胶支座的减隔震能力下降;不同特性的地震动激励对桥梁的地震能量反应有显著影响,在强震持时较长、卓越周期与隔震结构自振周期接近时,桥梁的地震能量反应较大;铅芯橡胶支座不宜应用于软土场地的桥梁隔震。
The energy response equations of the seismically isolated continuous beam bridge are established based on the energy equilibrium theory. Based on FEA software SAP2000, the seismic energy response analyses of the continuous beam bridge without seismically isolated and with lead rubber bearing seismically isolated are carried out under the bidirectional excitation of 4 typical ground motion records. The results show that most of total seismic input energy (about 80%) of the bridge is consumed by hysteretic energy dissipation of lead rubber bearing, and the lead rubber bearing can reduce the structure inelasticity deformation and protect the safety of the main structure. The structure of lead rubber bearing has greater effect on the seismic energy response of the isolated continuous beam bridge. Larger diameter of lead core and larger stiffness ratio of the bearing can decrease the bearing ability of seismic responses reduced and isolated. Different characteristics of earthquake wave have the significant effect on the seismic energy response of bridge. Especially, when the lasting time of seismic wave becomes longer or the predominant period of earthquake wave approaches the natural period of seismically isolated bridge, the seismic energy response of bridge is larger. The lead rubber bearing is not suitable to be applied in the seismic isolation of the bridge under the condition of soft soil site.