梯形截面斜拉桥竖向涡振分析数值模拟方法比较

Comparison of Numerical Simulation Methods for Vertical Vortex Induced Vibration(VIV)Analysis of Trapezoidal Cross-section Cable-stayed Bridge

采用Ansys有限元数值模拟平台,以大跨度梯形截面斜拉桥节段模型为研究对象,分别通过单、双向流固耦合方法对节段模型进行竖向涡激振动的有限元分析,总结出从1 m/s到15 m/s的低风速下节段模型的升力和阻力随时间的变化规律.通过对比分析得出,双向流固耦合方法中升力和阻力的模拟结果较好,节段模型的竖向振动明显且具有周期性,这说明双向流固耦合方法模拟竖向涡激振动优于单向流固耦合方法.比较了两种方法求得的涡振锁定区间,发现双向流固耦合方法的锁定区间较长,双向流固耦合造成的动能耗散是锁定区间变长的重要原因.最后通过理想平板理论与数值模拟的结果对比验证了双向流固耦合的合理性.

In this paper,the Ansys finite element numerical simulation platform is used to study the segmental model of the long-span trapezoidal cross-section cable-stayed bridge.The finite element analysis of the vortex-induced vibration of the segment model is carried out by the single and bidirectional fluid-solid coupling methods.The variation of lift and drag over time in the segmental model with low wind speed from 1 m/s to 15 m/s is summarized.Through a comparative analysis,it is found that the simulation results of lift and drag in the two-way fluid-solid coupling method are better.The vertical vibration of the segment model is obvious and periodic,which indicates that the bidirectional fluid-solid coupling method simulates vortex-induced vibration better than the unidirectional fluid-solid coupling method.The vortex-locking interval obtained by the two methods is compared.It is found that the locking interval of the bidirectional fluid-solid coupling method is longer,and the dynamic energy dissipation caused by the bidirectional fluid-solid coupling is an important reason for the longer locking interval.Finally,the validity of bidirectional fluid-solid coupling is verified by comparing the results of ideal plate theory with numerical simulation.