山区特大跨径桥梁桥址处风特性实测研究

Field Measurement Study on Wind Characteristics at theSite of a Large-span Mountainous Bridge

为研究山区桥址处的风场特性,基于西南山区某特大桥结构健康监测系统,对桥址处实测风场特性进行分析,并与规范推荐值比较。结果表明:1)大部分风速时程处于平稳状态,横向脉动风速的非平稳性高于纵向脉动风速;2)实测风速时程平均风速有跳变波动,平均风向保持平稳;3)各向湍流强度、阵风因子在低风速区段随平均风速的增大而减小,在高风速区段随平均风速的增大而趋稳;4)实测纵向阵风因子超过规范推荐值,纵向阵风因子与湍流强度具有较强的相关性,实测拟合曲线较Ishizaki推荐值偏小;5)实测功率谱值在低频区逐渐增大,在高频区逐渐减小,Von Karman经验谱能描述实测数据的脉动特性。该研究结果可为同类桥梁结构抗风设计提供依据。

In order to study the wind field characteristics at the site of a mountainous bridge,this paper analyzes the measured wind field characteristics at the bridge site and compares them with the recommended values in the guidelines based on the structural health monitoring system of a large-scale bridge in the southwest mountainous area.The research results show that:1)most of the wind speed time series are in a steady state,and the non-stationary of the lateral fluctuating wind speed is higher than that of the longitudinal fluctuating wind speed;2).The measured wind speed time series have abrupt fluctuations in average wind speed,while the average wind direction remains stable;3).The turbulence intensity in all directions and gust factor decrease with the increase of the average wind speed in the lower range of average wind speed,and remains stable with the increase of the average wind speed in the higher range of average wind speed;4).The measured longitudinal gust factor exceeds the recommended value in the code.There is a strong linear correlation between the longitudinal gust factor and the turbulence intensity,and the fitted curve based on the measured data is smaller than the recommended value by Ishizaki;5).The measured power spectral density gradually increases in the low-frequency range and decreases in the high-frequency range,and the Von Karman empirical spectrum can describe the fluctuating characteristics of the measured data.The research results can provide a basis for wind-resistant design of similar bridge structures.