桥梁气动导数的识别及模型参数对气动导数的影响

Identification of Flutter Derivatives of Bridge Deck and the Effects of the Model Parameters

提出了一种利用节段模型的自由振动响应数据识别桥梁断面气动导数的新方法—总体最小二乘时域法，该方法试验装置简单，避免了识别过程中参数选择带来的影响并且具有很高的精度和收敛性。针对自由振动测试技术在高风速下因竖弯方向气动阻尼太大、信号衰减过快导致识别不能进行的问题，本文改变模型的质量、质量惯矩及扭弯频率比进行了一系列试验，说明可以通过增加模型质量和质量惯矩的方法得到足够用于桥梁颤振分析的气动导数。将得出的江阴桥模型的试验结果与Ｓｃａｎｌａｎ方法的结果进行了对比，并且根据它算出的颤振风速在全桥气弹模型上得到了验证。

A new system identification technique—the global least square method in time domain has been developed to extract flutter derivatives of bridges from the free vibration data of section model test.The method is simple with good accuracy and convergency and avoids the selection of some parameters during the identification.To solve the problem that the aerodynamic damping is too large at high wind velocity,a set of experiments with different masses,inertial moments and frequency ratios of vertical torsional vibrations of the model were conducted. It is demonstrated that enough data for flutter analysis can be extracted by improving mass and inertial moment of the model.The flutter derivatives of Jiangyin bridge identified by the method were compared with those by scanlan′s technique,and the flutter wind velocity calculeted was verified through the aeroelastic test of the full model.