非平稳强风速下大跨度悬索桥的非线性风振响应研究

With the rapid increase of bridges span and the frequency occurrence of strong typhoons, the influence of non-stationary wind speed in strong typhoons on the wind-resistance performance of long-span suspension bridges cannot be ignored. A pure time-dependent analysis method of nonlinear wind-induced responses of long-span suspension bridges under non-stationary wind speed in strong typhoons is developed in this project. Firstly, different strong typhoon wind speed models with various non-stationary properties are simulated based on the measured strong typhoons and the spectral representation method, respectively. The correlation of wind speed along the bridge is also considered. Secondly, a time-dependent nonlinear aerodynamic force model with arbitrary non-stationary input is established based on nonlinear differential equations, and then the aerodynamic force time-histories of bridge girders under non-stationary random wind speed models are calculated based on the CFD simulation, the parameters of static force, self-excited force and buffeting force in the time-dependent aerodynamic force model are also identified by using the nonlinear least square method, respectively. Subsequently, different strong typhoon wind speed models and the time-dependent aerodynamic force model, are solved by coupling with three-dimensional nonlinear finite element bridge models, and the simulation results are validated through the comparison with the measured vibration responses of long-span suspension bridges under strong typhoons and the buffeting tests in multi-fan actively-controlled wind tunnel, respectively. Finally, the time-frequency analysis and the nonlinear dynamic method are used to compare the influence of non-stationary and nonlinear characteristics in buffeting responses for long-span suspension bridges under different non-stationary wind speeds, respectively. The research result is the breakthrough and perfection of the basic theory for bridges wind-resistance study, as well as provides an important reference for the revised wind-resistance design specification and the construction of long-span bridges.

随着桥梁跨径增大和强台风频发，强台风的风速非平稳特性对大跨度悬索桥抗风性能的影响不容忽视。本项目拟发展非平稳强台风风速下大跨度悬索桥的非线性风振响应的纯时域分析方法，首先基于实测强台风和谱表示法分别模拟不同非平稳特性的强台风风速模型，并考虑风速的展向相关性；其次，基于非线性微分方程组，构建适用于任意非平稳输入的非线性气动力时域模型，并通过CFD计算主梁断面在非平稳风速下的气动力时程，采用非线性最小二乘法分别识别出该气动力模型中静力三分力、自激力和抖振力的参数；再次，将非平稳强台风风速模型、非线性气动力时域模型与三维桥梁非线性有限元模型耦合求解，并利用实测强台风下桥梁振动响应和多风扇主动控制抖振试验分别进行对比验证；最后，结合时频分析和非线性动力学方法对比分析不同非平稳风速对桥梁抖振响应的非平稳和非线性特性影响。研究结果是桥梁抗风研究基础理论的突破和完善，可为桥梁抗风设计规范修订和大跨度桥梁建设提供重要的参考价值。

本项目针对我国沿海地区强台风非平稳特征和大跨度悬索桥的风振非线性行为问题，发展了非平稳强台风风速下大跨度悬索桥的非线性风振响应的纯时域分析方法，首先分析了大跨桥梁桥址区超强台风“利奇马”的非平稳风场特性，包括平均风速风向，紊流强度，阵风因子，紊流积分尺度和紊流功率谱密度，以及基于copula函数的风速-温度相关性，超强台风“利奇马”历经时呈现出高斯非平稳性，实测风谱与Kaimal谱吻合相差较大，实测风谱总体偏低，温度与风速之间存在对称厚尾结构变量的耦合关系；其次，基于频率-波数谱方法生成大跨悬索桥桥址区高斯脉动风场及非高斯脉动风场，对比了高斯风场与非高斯风场下大跨度悬索桥的抖振响应，并分析了加劲梁高度与地表粗糙两个风场重要因素对该桥梁抖振响应的影响，结果显示高斯与非高斯风场下的悬索桥抖振响应RMS值差别不明显，加劲梁离水面越低，地面粗糙度越大，桥梁抖振的位移响应越大。然后，基于Priestley演变谱，选取了两种典型的均匀调制函数和非均匀调制函数建立了不同非平稳风场模型，并与目标值进行了对比验证；再基于非线性微分方程组建立适用于非平稳输入的桥梁气动力时域模型，对比分析了四种不同非平稳风场下分体箱梁悬索桥的非线性风振响应，并基非线性动力学理论揭示了主跨跨中位移响应的非线性和非平稳特征。最后，研究了不同紊流作用下竖向上下稳定板、附属设施（风障与检修轨道）、隔涡板对大跨度闭口箱梁悬索桥的颤振性能、静风失稳涡振性能的提升效果，获得了最优的稳定板、附属设施和隔涡板的控制方案及机理。因此，本项目精确地预测非平稳、非高斯强台风下大跨悬索桥的非线性风振响应并实现了不同气动措施的有效控制，研究成果已用于保障多座大跨悬索桥抗风安全，具有较好的经济与社会效益，并发表了相关的SCI论文4篇、授权发明专利7个，软件著作权1项，获得了2021年广东省科技进步二等奖一项和中国公路学会科学技术一等奖一项。