地震和波浪联合作用下大跨度斜拉桥的动力响应研究

Research on Dynamic Responses of Long-Span Cable-Stayed Bridge Under Combined Earthquake and Wave Action

为揭示地震和波浪荷载联合作用对大跨度跨海桥梁的影响,以某大跨度跨海斜拉桥为背景,对其动力响应进行研究。采用ANSYS软件建立桥梁空间有限元模型,选取斯托克斯(Stokes)二阶波理论,利用CFD模块模拟波浪荷载作用,基于特克斯特拉(Turkstra)组合规则考虑地震和波浪荷载的联合作用,分析在地震和波浪分别作用和联合作用下桥梁结构的横向位移。结果表明:通过比较不同波高下的桥塔塔顶与主梁主跨跨中横向位移相对差值,发现随波浪荷载的增加,主梁主跨跨中横向位移增幅比较显著;地震和波浪联合作用时桥梁结构的动力响应并不是两者单独作用时桥梁动力响应的简单代数叠加,波浪荷载的存在改变了桥梁动力响应的峰值大小以及出现峰值的时刻;地震和波浪联合作用比波浪单独作用时桥梁结构动力响应明显增大,在跨海桥梁设计时,建议考虑地震和波浪荷载联合作用对结构的影响。

An existing long-span sea-crossing cable-stayed bridge is used as a case to reveal the combined effect of seismic and wave loads on the long-span sea-crossing bridge.The dynamic responses of the bridge were analyzed.A spatial finite element model of the bridge was developed in ANSYS to analyze the lateral displacement responses of the bridge structure under seismic loads and wave loads,respectively,and the combined seismic and wave actions as well.Specifically,the Strokes wave theory is adopted,and the CFD software is used to simulate the wave actions,and based on the Turkstra combination,the combined effect of seismic and wave loads is estimated.It is shown that under different wave heights,the pylon-head lateral displacement responses and the midspan girder lateral displacement responses of main span are varying,as the increase of the wave loads,the midspan girder lateral displacement responses of main span are obviously intensified.The dynamic responses of the bridge structure under the combined earthquake and wave actions do not mean the simple algebraic superposition of the dynamic responses induced by either earthquakes or waves.The existence of wave loads impacts the peak dynamic responses of the bridge and the peak time.Under the combined earthquake and wave actions,the dynamic responses of the bridge structure are more intense than those caused by the pure seismic loads or wave loads.It is suggested that the impact of combined earthquake and wave actions be considered in the design of sea-crossing bridges.