高斯流场中单自由度线性体系非高斯振动响应试验研究

Experimental study on non-Gaussian dynamic responses of a single-DOF linear system subjected to Gaussian-velocity turbulence

对于风湍流等高斯分布流速场中的线性结构体系,当考虑荷载中脉动流速二次项的影响时,理论上其振动响应将呈现非高斯分布特性。基于调试得到的不同粗糙工况高斯流场,开展了单自由度线性体系顺流向振动响应测试,研究了单自由度线性体系加速度响应的非高斯分布特性,分析了粗糙度对响应非高斯成分的影响,讨论了三种常见非高斯概率密度逼近方法对响应的拟合效果。试验结果表明:试验高斯流场中单自由度线性体系的顺流向加速度响应主要呈现出尖峰非高斯分布特征,且随着紊流度的提高,响应非高斯性有增强的趋势;响应的非高斯概率密度宜采用高斯混合模型方法进行拟合。

For linear elastic structures subjected to the fluctuating pressure of Gaussian-velocity turbulence,such as wind,dynamic responses or behaviors of the structures will show non-Gaussian distribution due to the quadratic term of fluctuating velocity theoretically.An experiment research on the dynamic responses and non-Gaussian characteristics of a single-degree-of-freedom(SDOF)linear elastic model subjected to Gaussian-velocity turbulence with different turbulence intensity was carried out.The non-Gaussian acceleration responses of the linear SDOF model as well as its correlation with turbulence intensity were analyzed.Finally,three approximation models with non-Gaussian probability density function(PDF)were discussed.The experiment results indicate that the acceleration responses of the SDOF model are of non-Gaussian distribution with high kurtosis of the PDF.With the increase of turbulence intensity,the kurtosis of non-Gaussian PDF will be magnified.The results also show that the Gaussian mixture model is much more valid for approximating non-Gaussian PDF compared to the Gram-Charlier series or Edgeworth series.