台风边缘区风场特性及其作用下高耸桅杆结构风效应实测研究

Field measurements of wind characteristics at periphery of typhoons and wind effect on high-rise guyed masts

以深圳356 m气象梯度塔记录的风速时程数据为基础,分析了台风“圆规”边缘区风场平均风速、湍流度及风谱特性,并进一步探讨了台风作用下梯度塔的风致响应特征。结果表明:台风边缘区域大风时段风剖面指数均值为0.243,高度40 m以下湍流强度介于GB 50009—2012《建筑结构荷载规范》中C类与D类场地之间,高度320 m处湍流强度则接近C类场地的;von Karman谱与高度320 m处实测风谱吻合较好,但与低空实测谱存在一定差异;台风激励下梯度塔以横风向振动为主,且风振多模态参与特征明显,纤绳振动不可忽略;结构加速度响应幅值对梯度塔的模态频率和阻尼存在一定影响;结构x向和y向前三阶模态频率整体呈现随加速度响应增大而减小的趋势;阻尼比的识别结果较为离散,y向的前三阶和x向的一阶模态阻尼比随结构加速度响应增大而增大,而x向的二阶和三阶模态阻尼比则随响应增大呈减小的趋势。

Based on the wind speed records from the 356 m high Shenzhen Meteorological Gradient Tower(SZMGT), the characteristics of mean wind, turbulence and wind spectrum at the periphery of typhoon Kompasu were analyzed, and the wind effect on the SZMGT were further investigated. It is observed that the mean value of wind profile index during high wind speed period is 0.243 and the low-altitude turbulence intensity is between Class C and Class D sites of GB 50009—2012 ‘Load code for the design of building structures', while the high-altitude turbulence intensity is close to Class C site. The measured wind spectrum at the height of 320 m is consistent with the von Karman spectrum, but there is a certain difference at the low altitude. During Kompasu, the SZMGT mainly vibrated in the crosswind direction, the multimodal participation for the response of SZMGT was very obvious, while the effect of rope vibration was not negligible. The acceleration amplitude had a certain influence on the modal frequency and damping of SZMGT. The modal frequencies of the first three modes in both x and y directions tend to decrease with increasing responses. The identified damping ratios are relatively discrete. The damping ratios of the first three modes in y direction and the first mode in x direction tend to increase with increasing responses, while the damping ratios of the second and third modes in x direction tend to decrease with increasing responses.