山区强风作用下大跨桥梁非平稳抖振响应精细化分析

山区复杂地形地貌使得桥梁容易遭受非均匀、非平稳来流的作用，复杂的风场环境严重威胁到桥梁的抗风安全。山区风场特性和桥梁非平稳气动力研究的不足严重影响山区强风作用下桥梁抖振响应的预测精度。本项目基于现场实测结果，采用理论分析和数值模拟方法，对山区强风作用下大跨桥梁非平稳抖振响应精细化分析展开研究。首先，发展一种非平稳风速时变特征统一建模方法，结合风场实测数据和CFD地形模拟结果，建立山区桥址区非平稳风速的有效模型。进一步，开展非平稳气动力数值试验，研究桥梁断面在山区非平稳风场下的气动力特性，基于准定常理论建立非平稳气动力模型，并识别桥梁非平稳气动力参数。最后，在上述工作基础上，建立山区风作用下大跨桥梁非平稳抖振响应高效频域分析方法，开展山区风作用下桥梁非平稳抖振可靠性研究，探究山区风非平稳特征对大跨桥梁抖振可靠性的影响。通过本项目的研究，可为山区大跨桥梁抗风性能的可靠预测提供参考。

The complex terrain and landforms of mountainous areas make bridges susceptible to the action of nonuniform and nonstationary winds, and the complex wind environment seriously threatens the wind-resistance safety of bridges. The lack of researches on the characteristics of winds in mountainous areas and the nonstationary aerodynamic forces of bridges seriously affects the accuracy of predicting buffeting response of bridges under strong winds in mountainous areas. In this project, the theoretical analysis and numerical modeling methods will be utilized to investigate the refinement analysis of nonstationary buffeting response of long-span bridges under the action of strong winds in mountainous areas based on the field measurement results. Firstly, a generalized modeling method for time-varying characteristics of nonstationary winds is developed. Combined with the measured wind data and the terrain modeling result by CFD, an effective model of nonstationary winds at bridge sites in mountainous areas is established. Furthermore, the numerical tests of nonstationary aerodynamic forces are carried out to study the characteristics of aerodynamic forces of a bridge section under the nonstationary wind field in mountainous areas. The models describing the nonstationary aerodynamic forces are established based on the quasi-steady theory and their nonstationary aerodynamic parameters are identified. Finally, based on the work above, an efficient frequency-domain method for analyzing the nonstationary buffeting response of long-span bridges under the action of winds in mountainous areas is established. The nonstationary buffeting reliability of bridges under the action of winds in mountainous areas is studied to explore the influence of the nonstationary wind characteristics on the buffeting reliability of long-span bridges. Through the research in this project, it can provide a reference for the reliable prediction of the wind-resistant performance of long-span bridges in mountainous areas.