桥梁颤振导数与气动导纳关系的试验验证  

Test verification for relations between bridge flutter derivatives and aerodynamic admittances

作　　者：张伟峰 张志田 张显雄 陈政清 ZHANG Weifeng;ZHANG Zhitian;ZHANG Xianxiong;CHEN Zhengqing(Hunan Provincial Key Lab for Wind Engineering and Bridge Engineering, School of Civil Engineering,Hunan University, Changsha 410082, China)

机构地区：[1]湖南大学土木工程学院风工程与桥梁工程湖南省重点实验室,长沙410082

出　　处：《振动与冲击》2018年第5期28-35,共8页Journal of Vibration and Shock

基　　金：国家自然科学基金项目(51578233;51178182)

摘　　要：桥梁断面的气动导纳,除了利用风洞试验直接识别外,Scanlan通过假定Wagner函数和Kussner函数等效提出了利用颤振导数表示的气动导纳关系式,Hatanaka等提出利用"等效"的Theodorsen函数表示的气动导纳。这两种方法虽然简化了气动导纳的识别,但是在逻辑上都存在问题。本文利用风洞试验,识别了平板断面和长宽比为4的矩形断面的颤振导数和气动导纳函数。通过比较识别的气动导纳与利用上述两种方法计算的气动导纳,验证了这两种方法的不合理性。研究结果表明:通过等效的阶跃函数推导的气动导纳函数,因为忽略了高阶运动模式,所以导致识别的气动导纳随着折算频率的增加,与试验直接识别的气动导纳的差距逐渐增大,并最终趋向于一个极限值;这种方法仅在脉动风波长远大于断面特征长度时是适用的;根据等效的Theodorsen函数表示的气动导纳函数,在低频范围内也与直接试验结果较为接近,但是在高频范围内却表现出周期性的波动,而且对于钝体的矩形断面这种波动性更大。这种波动是由于采用了某种等效的Theodorsen函数来描述物体的气动性能,在Theodorsen函数变化后,却保持Theodorsen函数的组成函数维持不变这种逻辑上的错误造成的。Besides identifying them directly from wind tunnel tests,aerodynamic admittance functions of bridge sections could be expressed using alternative methods.Through assuming Wanger function to be equivalent to Kussner function,Scanlan proposed using bridge flutter derivatives to express aerodynamic admittance functions.Hatanaka et al proposed using‘equivalent’Theodorsen functions to express aerodynamic admittances.Although both of them simplified identifying aerodynamic admittances,there were logical problems in the two methods.Here,flutter derivatives and aerodynamic admittance functions of a flat plate section and a rectangular section with a aspect ratio of4were identified with wind tunnel tests.Then,through comparing the measured aerodynamic admittances with those calculated using the above two methods,irrationality of the two methods was verified.The results indicated that with increase in the reduced frequency,the difference between the calculated aerodynamic admittances using the method of equivalent indicial functions and the measured ones gradually increases and tends to a limit value due to ignoring higher order motion modes,this method is applicable only when the wave length of fluctuating wind is much larger than the characteristic length of bridge sections;the aerodynamic admittances calculated using the equivalent Theodorsen functions are close to the measured ones within a lower frequency range,while they have a periodic fluctuating within a higher frequency range;for rectangular section of bluff bodies,this fluctuating becomes more significant;this fluctuation is due to adopting a certain‘equivalent’Theodorsen function to describe objects’aerodynamic performance,once Theodorsen function changes,but its component functions remain unchanged to cause a logical mistake.

关 键 词：桥梁 风洞试验 颤振导数 气动导纳 阶跃函数 Theodorsen函数 

分 类 号：U441.2[建筑科学—桥梁与隧道工程]