行波及相干效应对超千米跨度斜拉桥多维多点随机地震响应的影响

The Influence of Traveling Wave and Coherent Effects on Multi-dimensional and Multi-point Random Seismic Response of Super Long Span Cable Stayed Bridge

为了研究行波及相干效应对超千米跨度公铁两用斜拉桥地震响应的影响,基于通用有限元软件ANSYS,借助高效的虚拟激励法分别得到考虑两种效应的结构地震响应值,通过对比研究,结果表明:(1)仅考虑行波效应时,在视波速取500 m/s工况下,主梁纵向位移和竖向位移出现最大均方根值,行波效应对主梁纵向位移响应影响最为显著;(2)仅考虑相干效应时,主梁纵向位移和横向位移在部分相干工况下出现最大均方根值,主梁跨中横向位移的均方根值为0.274 m,较一致激励(完全相干)增大了126.4%;(3)两种效应对结构1号边墩、2号辅助墩和3号主塔的不同地震响应的影响程度存在较大差异,需具体响应具体分析。通过各具体工况下的结果对比,得出超大跨度斜拉桥地震响应分析考虑行波和相干效应十分必要的结论。

In order to study the influence of traveling wave and coherent effects on seismic response of the super long span railway double purpose cable stayed bridge,the seismic response of the structures with two effects are obtained with the aid of the efficient virtual excitation method based on the general finite element software ANSYS. The results of the comparative study show that：（ 1） when only the traveling wave effect is considered,the effect of the traveling wave on the longitudinal displacement of the main beam is the most significant,while the apparent wave velocity of 500 m / s is taken with the maximum root mean square value of both the longitudinal displacement and the vertical displacement of the main beam;（ 2） when only the coherence effect is considered, the longitudinal displacement and transverse displacement of the main beam appear under partially coherent conditions,the root mean square value of the transverse displacement of the main beam is 0. 274 m,and the uniform excitation（ totally coherent）increases by 126. 4%;（ 3） the seismic responses of the two effects differ much in the structures of No. 1side pier,No. 2 auxiliary Pier and No. 3 main tower,and need to be analyzed specifically. By comparing the results of the specific conditions,we obtain that it is necessary to include traveling waves and coherent effect in the analysis of seismic response of large span cable-stayed bridges.