山地城市钢桥杆件涡激振动数值模拟研究

Study on Numerical Simulation of Vortex-induced Vibration of Steel Bridge Member in Mountain City

以重庆朝天门大桥的典型杆件作为研究对象,将构件简化为弹簧-阻尼-质量二维系统,利用FLUENT软件建立数值风洞,对山地城市钢拱桥杆件风振机理进行研究。通过弱耦合的方法对杆件的涡激振动进行数值仿真模拟,全程应用四阶Runge-Kutta法求解,进行数据的传递。数值分析结果表明:0°风攻角下,风速为45 m/s时涡脱频率与结构的固有频率十分接近,位移最大值为65.54 mm,断面发生涡激共振,此时呈现周期性交替的涡街,且涡的大小和涡距较为均匀;风速为45 m/s时,随着风攻角的变化,最大位移及最大升力均有变化;随着阻尼比的递增,最大位移呈现递减趋势,增大结构的阻尼比在一定程度上能限制共振时的位移幅值。

Taking a typical member of Chaotianmen bridge in Chongqing as the study object,the component was simplified as a spring-damped-mass two-dimensional system,and a numerical wind tunnel was established by using FLUENTsoftware to study the wind-induced vibration mechanism of steel arch bridge member in the mountain city.The vortex-induced vibration of the member was numerically simulated based on the weak coupling method.The whole progress was solved by fourth-order Runge-Kutta method,and the data were transmitted. The numerical results show that at 0° wind attack angle,when the wind speed is 45 m/s,the vortex shedding frequency is very close to the natural frequency of structure,the maximum displacement is 65. 54 mm,the vortex resonance occurs at the cross section.At this time,the vortex of periodic alternation is presented,the size and the distance of vortex are uniform.When the wind speed is 45 m/s,the maximum displacement and maximum lift vary with the change of wind attack angle.With the increase of the damping ratio,the maximum displacement decreases.The amplitude of the displacement response in the resonance can be effectively limited by increasing the damping ratio of structure.