结构构件阻尼比对大跨度悬索桥地震响应的影响

摘要

对某大跨度悬索桥进行3向地震反应谱响应分析，考虑不同构件阻尼比对悬索桥地震响应产生的不同影响．首先通过设定不同构件阻尼比的情况进行模态分析，以振型贡献系数最大值所对应的模态阻尼比作为一个方向结构的整体阻尼比；然后采用反应谱法获取该方向上结构的地震响应．通过对结构的地震响应分析发现，不同构件阻尼比对结构地震响应的影响不容忽视；《公路桥梁抗震设计细则》中对悬索桥整体阻尼比不宜大于0．02的建议会使结构地震响应偏大，从而使桥梁设计偏于安全．%The influence of damping ratios of the structural components should be considered in the responses of a long-span suspension bridge under earthquake effect in three dimensions by the response spectrum method. The modal analysis is conducted by taking into account the different structural component damping ratios.And then the integral damping ratio of the structure is determined by using the mode damping ratio in terms of the maximum mode contribution coefficient.After that,the earthquake responses of a suspension bridge are evalua-ted by the response spectrum method.Results indicate that the influence of the structural components damping ratios on the structural earthquake response should not be ignored.The integral damping ratio value,being 0.02 for a suspension bridge,as recommended by the “Guidelines for Seismic Design of Highway Bridges”,might lead to a conservative but secure design on the structure.