山区非高斯风作用下的大跨桥梁抖振响应研究

Large numbers of mountainous long-span bridges spring up with the improvement of the traffic and transportation network. Wind characteristics of the mountainous area are more complex than those of the open area such as the plain. Meanwhile, long-span bridges are sensitive to the wind action. Therefore, the characteristics of the wind in the mountainous area and its effect on the bridge response attract considerable attention. Current research shows that the power spectrum of the mountainous topographic wind is obviously different from the common counterparts. Moreover, it shows the non-Gaussianity. However, the influence of these factors on the bridge response is not well assessed. Hence the following research will be carried out in this project. (1) Based on field measurement and the wind tunnel test of the terrain model, fluctuating wind characteristics of the mountainous area will be investigated to propose reasonable power spectrum and probability distribution models. (2) By utilizing analytical methods for non-Gaussian case, the simplification for the relationship between the correlation functions of the non-Gaussian process and the corresponding Gaussian process will be discussed. Besides, the reduced model describing the correlation of the non-Gaussian power spectrum and the corresponding Gaussian counterpart will be established. The high simulation efficiency for the time history of the non-Gaussian fluctuating wind can be expected through the study. (3) Through the combination of the finite element analysis software and self-compiled program, the efficient calculation for the buffeting response of bridges is investigated in the time domain. According to the time history of the response, the related moments, probability characteristics and extreme value can be analyzed. Afterwards, the evaluation of the effect on the response resulting from the spectral characteristics and the non-Gaussianity of the fluctuating wind in the mountainous area can be summarized. The aforementioned research content can offer a reference for the reasonable estimation of the wind-resistant performance about bridges under the action of the mountainous topographic wind.

随着交通运输网络的完善，山区大跨桥梁不断涌现。由于山区风特性比平原等开阔地区更为复杂，且大跨桥梁对风的作用较为敏感，因此山区风特性及其作用下的桥梁响应引起了重点关注。现有研究表明，山区风的功率谱与常用的功率谱形式有较大差异，且存在非高斯特性，而这些因素对桥梁响应的影响还没有具体地进行评估。因此，本项目拟开展如下研究：(1)基于现场实测和地形模型风洞试验，研究山区脉动风特性，提出合理的山区风谱和概率分布模型。(2)利用非高斯分析方法，探讨非高斯过程和高斯过程之间相关函数关系的简化，构建表征非高斯谱和高斯谱之间关系的简化模型，实现非高斯脉动风时程的高效模拟。(3)结合有限元分析软件和自编程序，探讨桥梁抖振响应在时域上的高效计算。根据响应时程，分析响应统计矩、概率特性及其极值，评估山区脉动风频谱特性和非高斯特性对响应的影响。通过上述研究内容，为山区风作用下桥梁抗风性能的合理评估提供参考。

针对山区非高斯风场，本项目开展了非高斯脉动风的概率模型构建、非高斯脉动风场的模拟、非高斯风场作用下的桥梁抖振响应研究，评估了脉动风场的非高斯特性对桥梁风致响应的影响，为大跨度桥梁的抗风可靠性提供理论参考。.主要研究成果如下：.（1）通过不同非高斯概率模型的对比，汇总不同模型的优势，提出了HPM-JTM混合模型，应用于非高斯脉动风的概率描述。.（2）基于HPM-JTM混合模型，构建非高斯相关函数与标准高斯相关函数之间的显式关系，避免了模拟过程中的迭代，实现了非高斯风场的有效模拟。.（3）探讨了风场非高斯特性对桥梁抖振响应的影响，结果表明：非高斯风场作用下，桥梁抖振响应均方根值大于高斯风场情况，响应的概率特性仍趋于高斯分布。