大跨连续梁桥纵向减震机理和减震效果分析

Analysis of Seismic Mitigation Mechanism and Effect on Longitudinal Direction of Long-Span Continuous Bridges

基于一座实际大跨度连续梁桥,分析比较了采用动力锁定装置、黏滞阻尼器和双曲面减隔震支座的减震机理和减震效果,讨论了这些减震装置的适用范围.结果表明:动力锁定装置不耗散地震能量,在活动墩处设置该装置,可以合理分配梁体的地震惯性力,但同时结构周期减小,可能增加梁体总的惯性力;黏滞阻尼器不改变结构的周期、振型等动力特性,主要通过阻尼力消耗地震能量,减小结构动力反应;采用双曲面减隔震支座后结构的周期延长,阻尼耗能能力增加,相对于基准模型,显著减小了固定墩的内力,但同时增加了活动墩墩梁相对位移.

Based on an actual long-span continuous bridge,the seismic mitigation mechanism and effect of Lock-up device,fluid viscous damper and double spherical seismic bearing were investigated and the applicable condition of these seismic mitigation devices are disscussed.The results show that lock-up devices do not dissipate seismic energy and can reasonably distribute the seismic inertial force of girder,but may increase the total inertial forces of girder.Fluid viscous dampers,which do not change the structural dynamic characteristics such as structural period and vibration shape,mainly dissipate the seismic energy and reduce structural dynamic response by damping force. Double spherical seismic bearings provide flexibility to lengthen the natural period of the bridge and increase the energy dissipation capacity.However,compared with the response of corresponding non-isolated bridges,the relative displacements between girder and pier increase while decreasing seismic forces of the fixed pier.