尾流激振情况下桥梁气动导数识别及误差分析

Flutter derivatives via wake-induced vibrations of bridge model and error analysis

对钝体桥梁模型在尾流激励下的随机振动进行辨识,得到气动导数。建立气动导数辨识误差因子,衡量辨识效果。在辨识过程中,通过输出协方差估计得到虚拟马科夫参数的时间序列,利用ERA方法辨识得到等效线性系统的状态矩阵并获得气动导数。在ERA框架内建立辨识结果的能量误差因子。通过与自由衰减振动的辨识结果相比对,讨论耦合系统的非线性本质。针对两种截面形式的试验结果表明,耦合系统的辨识误差与该系统的非线性有明显关联。

Flutter derivatives are identified via the wake-induced vibration of bridge deck model.The error index is proposed to evaluate the quality of the identified derivatives.Output covariance is utilized to obtain the Markov parameters of the system,which is subjected to ERA method,subsequently,for the extraction of flutter derivatives.The error index is established within the framework of ERA.The Effect of nonlinearity on the identification results is discussed through the comparison of the flutter derivatives and error index of the wake-induced random vibration and free decay vibration cases.It is shown,by the experimental results of two models with different sectional shapes,that the identification error is clearly related to the nonlinearity of the interactive system.