不同阻尼计算模式对斜拉桥地震响应分析的影响

大跨度斜拉桥阻尼组成复杂,各阶振型的阻尼差别较大。为了研究阻尼计算模式对斜拉桥地震响应分析结果的影响,以主跨448 m的杭州湾跨海大桥北航道桥为对象,对应用考虑结构阻尼分布影响的振型应变能比例阻尼理论、常数阻尼、Rayleigh阻尼理论的适用性进行分析。结果表明,地震响应结果与所用的阻尼理论有关,常数阻尼不能很好反映结构的阻尼特性,而Rayleigh阻尼模式的计算结果取决于选取的参考振型,在较大的频率范围内存在过大或过小估计结构阻尼的问题,具有很大的随意性。相比之下,振型应变能比例阻尼理论能够考虑斜拉桥阻尼的分布特性,比较合理。

Effects of Different Damping Modes on the Seismic Response of Cable-Stayed Bridges

The damping makeup of long-span cable-stayed bridge is complicated and every mode has distinct damping.In order to study the influence of different damping modes on the seismic analysis results of cable-stayed bridges,a case study was performed on the 448-meter-span scheme of Northern Channel Bridge in Hangzhou Bay Bridge.Modal strain energy proportional damping theory reflecting effects of the damping distribution was used in seismic response analysis of the bridge to check the applicability of commonly used constant damping and Rayleigh damping.It shows that the results of seismic response depend on the damping theory used in the analysis.Constant damping can not represent structural damping characteristics.The seismic response results of Rayleigh damping highly depend on the reference modes chosen.The damping characteristics are overestimated or underestimated by Rayleigh damping in large frequency range which shows great random.Modal strain energy proportional damping theory which reflects the distributing property of cable-stayed bridges is comparatively reasonable.