考虑行波效应的长联大跨径减隔震连续梁桥地震响应研究

Study of Seismic Response in Consideration of Wave Passage Effect for Long-Span Seismic-Isolated Continuous Beam Bridge with Long Continuous Units

为探讨行波效应对长联大跨径减隔震连续梁桥结构地震响应的影响规律,以某长联大跨径钢桁架连续梁桥为对象,建立了该桥采用双曲面球型减隔震支座进行减隔震设计的三维有限元分析模型,通过基于大质量法的非线性时程分析,对该桥考虑行波效应和一致激励下的地震响应进行了计算和对比分析。研究结果表明:行波效应对大桥地震响应的影响较为明显,且与一致激励工况相比,考虑行波效应后大桥内力响应可能发生明显增大,不利于结构安全,而导致响应增大所对应的地震波视波速则会随支座参数改变发生变化;同时主梁位移则随加载视波速的增加缓慢增大,在一致激励作用下达到峰值;在类似减隔震设计中,应考虑行波效应的影响以保证结构响应在安全范围内,主梁位移可偏安全地以一致激励所得结果为准。

To study the influential law of wave passage effect on the seismic response of long-span seismic-isolated beam bridge with long continuous units,a long-span steel truss continuous beam bridge was taken as the study object.The bridge is equipped with spherical seismic mitigation and isolation bearings with two curved surfaces.The three-dimensional finite element analytical model of the bridge was established.By using the non-linear time history analysis based on the large mass method,the seismic responses of the bridge considering the wave passage effect and uniform excitation were calculated and contrastively analyzed.The results of the study show that the wave passage effect has obvious effect on the seismic response of the bridge.Compared with the load case of uniform excitation,the internal force response of the bridge considering the wave passage effect will intensify,which is not favorable to the structure safety.The seismic wave velocity inducing the intensity of internal force response will change following the change of bearing parameters.The displacement of the main girder shows sign of slow increase as the increase of the seismic wave velocity,reaching the peak value under the action of uniform excitation.Therefore,it is necessary to take into consideration of the influence of wave passage effect in the similar seismic mitigation and isolation design to ensure that the structural response is within the safe range.To be safer,the main girder displacement can take the data gained under the condition of uniform excitation as the benchmark.