武汉阳逻长江公路大桥设计风速值的研究

Research on design wind-velocity of Yangluo Yangtse River Bridge in Wuhan

利用武汉市气象站1961～1999年的风的基本资料,分析了桥位周边平均风速、最大风速、大风日数、最多风向及频率、各风向平均风速及频率、历年的极值风速及大风危害等风的基本特征;建立了武汉市气象站1961～1995年的逐年最大风速序列(其中1989～1995年的逐年最大风速,通过与未受城市化影响的黄陂气象站的比较而进行了合理的订正)。根据建筑设计规范采用极值Ⅰ型曲线,并用两种参数估计方案,推算出武汉市气象站不同重现期(100,50,30a)10m高处10min平均年最大风速(基本风速)分别为19.4m/s,18.4m/s和17.8m/s。采用比值法求出,从气象站到大桥江边最大风速的增大系数为1.54,从而得到桥位区不同重现期(100,50,30a)10m高处10min平均年最大风速(设计风速)分别为29.9m/s、28.3m/s和27.4m/s。最后分析了大风在146m高度内的变化特征,并采用指数和对数法将设计风速外推到200m以下每10m高度层,可供设计、施工及将来维护参考。

Based on the data of wind at Wuhan Meteorological Station from 1961 to 1999, the elementary wind properties of the average wind velocity,the maximum wind velocity, the days of gales, the most occurring wind direction and its frequency, the average wind velocity and frequency in each direction, the yearly extreme velocity and loss caused by gale, etc near the bridge area are analyzed. The serial of the yearly maximum wind velocity at the station from 1961 to 1995 is built up(the yearly maximum wind velocity at the station from 1989 to 1995 are amended rationally by comparing with the data unaffected by urbanization at Huangpi Meteorological Station).According to the design code of building, the yearly maximum 10min averaged wind velocity at the height of 10m above surface at the station for different return periods (100,50,30a) is calculated as 19.4m/s,18.4m/s and 17.8m/s respectively, by adopting the function of Extreme I with two schemes of parameter estimation. A ratio 1.54(enlarging coefficient) of wind velocity from the station to the bridge area is calculated by using comparing method.So the yearly maximum 10min averaged wind velocity at the bridge area at the height of 10m above surface for different return periods(100,50,30a) is further calculated as 29.9m/s,28.3m/s, 27.4m/s respectively. Finally the changing characteristics of yearly maximum 10min averaged wind velocity under 146m is analyzed. Furthermore, using the exponent and logarithm functions ,the design wind velocity is extrapolated to every 10m layer within 200m high. They can be referred for designing, constructing and future's maintaining.