山区峡谷风环境桥梁断面气动力及大跨桥梁风致响应特征研究

The wind environment around bridge in mountainous-valley shows strong spatial heterogeneity and temporal instability. The wind loads and wind-induced response of bridge are also different from that on the flat ground and the method to analyze the responses of bridge in mountainous-valley according to the aerodynamic parameters that obtained in the uniform and conventional turbulent flow field is no longer suitable. Also, the conventional evaluation criteria are not applicable.. In this project, the spatial and temporal distributions of mean and turbulent wind speed in mountainous-valley are studied by field measurement, numerical simulation and wind tunnel test. Mathematical models that suitable for the wind parameters around bridge will be established at the same time. Based on the sectional model wind tunnel test, the effect of turbulence (turbulence intensity and length scale) on the self-excited force, buffeting force and the span-wise correlation of buffeting force on typical bridge girders will also be investigated and corresponding mechanical models could be obtained. The effect laws of turbulence and spatial and temporal uneven distribution of wind speed in mountainous-valley on the flutter stability, aerostatic stability and buffeting forces on long span bridge will also be studied. The wind resistant safety evaluation criteria for bridge in mountainous-valley will be established which provides a scientific basis for safety evaluation of long span bridges in mountainous region.

山区峡谷中的桥梁所处的风环境表现出强烈的空间非均匀性和时间上的非平稳性，桥梁的风荷载及风致响应特征与平原地区相比有明显不同，用均匀流场和常规紊流场条件下所得到的主梁气动参数计算桥梁结构的响应与峡谷风环境不再匹配，而常规的抗风安全评价标准亦不适用。. 本项目利用现场实测、地形数值分析和风洞试验，研究平均风和紊流风在山区峡谷中的空间和时间上分布规律，建立适合峡谷环境的桥梁设计风参数数学模型；通过节段模型风洞试验，研究紊流（紊流度和紊流积分尺度）对典型主梁断面的自激力、抖振力及其跨向相关性的影响规律，建立能够考虑山区峡谷风环境的典型桥梁断面自激力、抖振力和空间相关性的力学模型。在上述基础上，探索山区峡谷风在紊流特征、风速空间和时间分布的不均匀性对大跨桥梁颤振稳定性、静风稳定性和抖振荷载的影响规律，建立适合于山区桥梁抗风安全的评价准则，为山区大跨桥梁的抗风安全评价提供科学依据。

山区峡谷中的桥梁所处的风环境表现出强烈的空间非均匀性和时间上的非平稳性，桥梁的风荷载及风致响应特征与平原地区相比有明显不同，用均匀流场和常规紊流场条件下所得到的主梁气动参数计算桥梁结构的响应与峡谷风环境不再匹配，而常规的抗风安全评价标准亦不适用。. 本项目通过现场实测、数值分析和风洞试验，研究平均风和紊流风在山区峡谷中的空间和时间上分布规律，建立适合峡谷环境的桥梁设计风参数数学模型；通过节段模型风洞试验 ，研究紊流对典型主梁断面的自激力、抖振力及其跨向相关性的影响规律，建立能够考虑山区峡谷风环境的典型桥梁断面自激力、抖振力和空间相关性的力学模型。在上述基础上，探索山区峡谷风在紊流特征、风速空间和时间分布的不均匀性对大跨桥梁颤振稳定性、静风稳定性和抖振荷载的影响规律，为山区大跨桥梁的抗风安全评价提供科学依据。