拱桥板式吊杆风致涡振特性及等效静力计算

基于计算流体力学方法,采用流体力学软件FLUENT,建立风致涡振数值模拟模型,并与风洞试验和数值模型进行对比,验证所建立的涡振数值模拟方法可靠性后,以高宽比1∶6的板式吊杆为背景,进行风向、风速、阻尼比和长细比等因素对板式吊杆风致涡振特性影响研究,并通过理论推导和加载试算,提出考虑涡振作用的吊杆等效静力计算式。结果表明:吊杆风致涡振表现为等幅单频运动,最大振幅时的涡振频率与吊杆的弯曲振动频率一致,短边和长边迎风时吊杆的Strouhal数约为0.11和0.12;当吊杆阻尼比减小时,最大涡振振幅明显增大,涡振锁定区间相应扩宽;随着长细比减小,发生涡振的风速会相应增大,但对吊杆涡振的最大振幅无显著影响;在吊杆频率和阻尼比相近时,长边迎风的涡振起振风速和涡振振幅均比短边迎风大。

Vortex-Induced Vibration Characteristics and Equivalent Static Force Calculation of Plate Hanger on Arch Bridge

A numerical simulation model of vortex-induced vibration(VIV)was established by using the fluid dynamics software FLUENT based on computational fluid dynamics(CFD)method.By comparing with the results of the wind tunnel tests and numerical model,the reliability of the VIV numerical simulation method was verified.Then,taking the plate hanger with the height-to-width ratio of 1∶6 as background,the effects of wind direction,wind speed,damping ratio,slenderness ratio and other factors on the VIV characteristics of the plate hanger were investigated.The equivalent static force calculation formula considering VIV was presented by theoretical deduction and loading trial.Results show that the VIV of the hanger is the motion of the equal amplitude and the constant frequency.The vibration frequency of the hanger at the maximum amplitude of the VIV is the same as the bending frequency of the hanger.For the short-side and long-side windward cases,the Strouhal numbers of the hanger are about 0.11 and 0.12,respectively.With the damping ratio of hanger decreasing,the maximum VIV amplitude increases apparently and the lock-in range of VIV expands correspondingly.As the slenderness ratio decreases,the corresponding wind speed increases when the VIV occurs,while the maximum vibration amplitude of the hanger vortex has few changes.Under the condition of similar frequency and damping ratio of the hanger,the onset wind speed of VIV is larger for the long-side windward case than the short-side windward case,and so is the VIV amplitude.