台风作用下大跨度索承桥梁非平稳抖振精细化研究及实测验证

The buffeting responses of long-span cable-supported bridges are prominent under non-stationary typhoon actions. Obvious time-varying features are captured in aerodynamic forces, and the buffeting responses behave as typical non-stationary random processes. The buffeting responses of bridges can not be accurately predicted by the buffeting analytical theory of bridges based on the stationary assumption. Hence, a refinement study on non-stationary buffeting responses of long-span cable-supported bridges under typhoon actions is thus conducted in this project. The main research contents mainly include: (1) Analyze the non-stationary characteristics as well as their evolutionary features in the whole duration of measured typhoon winds, and establish effective models to characterize the featured parameters describing the non-stationary characteristics of typhoon winds. (2) Investigate the conditional simulation approach for the three-dimensional non-stationary fluctuating wind field of typhoon winds as well as the strategies to improve the simulation efficiency, and realize the refine and efficient simulation of typhoon wind field. (3) Investigate the characteristics of aerodynamic forces of bridges under non-stationary flow field, and establish models to describe the non-stationary forces of bridges considering the time-varying effect of typhoon winds; (4) Based on the work above, establish an equivalent linear time-domain method for analyzing the non-stationary buffeting responses of bridges under typhoon actions, and verify this approach with field-measured results. Then, conduct applications to long-span cable-supported bridges, such as Sutong Bridge, Runyang Bridge, etc. This project is aimed to enhance the current buffeting analytical theory of bridges, and is expected to lay the foundation for the reasonable and reliable prediction of wind-induced vibrations of long-span cable-supported bridges during typhoon conditions.

在非平稳台风作用下，大跨度索承桥梁抖振响应突出，结构气动力存在明显时变特征，桥梁抖振响应亦表现为典型非平稳随机过程。采用以平稳假设为基础的桥梁抖振分析理论，难以准确预测台风环境下的桥梁抖振响应。为此，本项目开展台风作用下大跨度索承桥梁非平稳抖振精细化研究。主要研究内容包括：(1)研究实测台风全过程非平稳特性及演化规律，建立描述台风非平稳特性参数的有效模型；(2)研究台风三维非平稳脉动风场条件模拟方法与模拟效率提升策略，实现台风场的精细与高效反演；(3)研究非平稳流场下的桥梁气动力特性，建立考虑台风时变效应的非平稳气动力模型；(4)在上述工作基础上，建立经过实测验证的台风作用下桥梁非平稳抖振等效线性时域分析方法，并结合苏通、润扬等大桥开展工程应用研究。本项目旨在进一步完善桥梁抖振分析理论，以期为台风环境下大跨度索承桥梁风振响应的合理与可靠预测奠定基础。

随着桥梁跨度的增加，台风作用下大跨度索承桥梁的抖振响应愈加突出。与良态风存在明显差异，台风具有突出的非平稳特征，使得传统方法难以准确预测桥梁风振响应。本项目结合江苏省多座大跨度索承桥梁，围绕台风非平稳特性与桥梁非平稳抖振的主题，综合理论分析、数值模拟、现场实测等研究手段，开展台风作用下大跨度索承桥梁非平稳抖振精细化研究及实测验证，主要研究内容及成果包括：（1）台风非平稳特性现场实测与特征参数建模。基于长期监测数据，开展了台风非平稳特性实测研究。对比分析了台风全过程非平稳紊流特征参数及其演化规律，建立了非平稳脉动风速演变谱密度与时变相干函数的有效模型。（2）台风三维非平稳脉动风场高效数值模拟。推导了考虑时变相干特性的台风三维脉动风场模拟方法，分析了非平稳风场模拟的计算效率及其主要影响因素，并联合降阶表征与快速傅里叶变换，建立了台风三维非平稳脉动风场高效模拟方法。（3）考虑台风时变效应的桥梁非平稳气动力建模。基于CFD研究了非平稳流场与典型桥梁断面的耦合作用，分析了典型桥梁构件的气动力特性及其规律。考虑台风时变相干效应与平均风速的时变特征，建立了大跨度索承桥梁非平稳时域气动力分析模型。（4）台风作用下桥梁非平稳抖振精细分析方法。根据台风环境下实测桥梁振动响应，研究了桥梁非平稳抖振特性及其演化规律，推导了“台风-桥梁”耦合时变系统的动力分析方程，从而建立了台风作用下大跨度索承桥梁非平稳抖振响应精细分析方法，并通过现场实测数据进行了验证。研究成果对现代桥梁抗风分析理论提供了有益补充，并已被应用于苏通大桥、张靖皋大桥、昂船洲大桥等国家重点桥梁工程的抗风设计或性能评估，可为台风多发区大跨度索承桥梁的安全服役与稳定运营提供理论与技术支撑。