Toward an Improvement in the Identification of Bridge Deck Flutter Derivatives
Toward an Improvement in the Identification of Bridge Deck Flutter Derivatives
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DOI：
10.1061/(asce)0733-9399(2009)135:8(771
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发表时间：
2009-08
期刊：
影响因子：
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通讯作者：
G. Bartoli;Stefano Contri;C. Mannini;M. Righi
中科院分区：
文献类型：
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作者：
G. Bartoli;Stefano Contri;C. Mannini;M. Righi
本文简要回顾了国内外桥梁颤振导数识别方法的发展现状，提出了一种新的基于统一最小二乘法（ULS）的改进统一最小二乘法，可同时从自由振动节段模型试验中提取气动弹性系数。相对于ULS的优点是更快，更好的收敛和精度的提高，由于在统一的误差函数的加权因子的引入。该方法已通过数值模拟噪声信号和实验的两个不同的桥面横截面：单箱和多箱梁截面模型的起伏和俯仰时间历程进行了验证。仿真信号分析表明，由于该问题的强病态性，部分系统参数很难辨识。然而，所有的对角和非对角的刚度和阻尼矩阵，显着有助于系统的输出分量的正确估计。与其他方法的改进进行了广泛的讨论。对于风洞试验情况下的识别程序的准确性进行了评估，通过比较测量信号和模拟通过估计的机械和气动系统参数与非常令人满意的结果。相对于许多以前的验证尝试，这种方法清楚地显示了识别算法的准确度。最后，对于所考虑的测试用例，该方法背后的线性模型似乎是该现象的物理学的可接受的近似。
This paper presents a short review of the state-of-the-art methods to identify bridge deck flutter derivatives and proposes a new algorithm to simultaneously extract the aeroelastic coefficients from free-vibration section-model tests, which is based on the improvement of the unifying least-squares (ULS) method and is therefore called modified unifying least-squares method. The advantages with respect to ULS are the faster and better convergence and the improvement in accuracy due to the introduction of weighting factors in the unifying error function. The method has been validated through numerically simulated noisy signals and experimental heaving and pitching time histories for two different bridge deck cross sections: a single-box and a multiple-box girder section model. The analysis of the artificial signals shows that a few system parameters are very difficult to be identified due to the fact that the problem is strongly ill-conditioned. Nevertheless, all the diagonal and off-diagonal components of the stiffness and damping matrices which significantly contribute to the output of the system are correctly estimated. The improvement with respect to other methods is extensively discussed. For the wind-tunnel test cases the accuracy of the identification procedure is evaluated through the comparison between measured signals and those simulated through the estimated mechanical and aerodynamic system parameters with very satisfactory results. With respect to many previous attempts of validation, this approach clearly shows the degree of accuracy that can be expected from the identification algorithm. Finally, for the considered test cases the linear model which stands behind the method seems to be an acceptable approximation of the physics of the phenomenon.