不同方法确定的雷击密度对防雷分类的影响

利用江西1955—2011年气象观测资料和2004—2011年雷电监测资料,对比分析了分别依照《建筑物防雷设计规范》（GB50057—2010,简称新规范）和（GB50057—94,简称旧规范）计算的年平均雷击大地密度（Ngn和Ngo）,计算了江西实际雷击大地密度,研究新规范的实施对防雷分类的影响。结果表明,年平均雷暴日小于116.40 d时,Ngn〉Ngo;大于116.40 d时,则相反;等于48.5 d时,两者相差最大,约为1.12次（/km2.a）。相较于旧规范,按照新规范划入第二类、第三类防雷建筑物数量偏多。按照新规范,计算得到的雷击大地的年平均密度比江西实测值大30%,即江西地区的同一建筑物,依照Ngn划定的建筑物防雷类别可能高于利用实测雷击大地密度计算结果划定的建筑物防雷类别。

EFFECT OF THE LIGHTNING DENSITY CALCULATED BY DIFFERENT METHODS ON LIGHTNING PROTECTION CLASSIFICATION

With 1955-2011 meteorological data and 2004-2011 lightning monitoring data of Jiangxi,the annual average lightning densities（Ngn and Ngo） are calculated in accordance with GB50057-2010（referred to as the new norm） and GB50057-94（referred to as the old norm）,and effect of executing of the new norm on lightning protection classification is analyzed.Results show that NgnNgo（NgnNgo） when the annual average thunderstorm days are less（larger） than 116.40 d and there is the largest difference between Ngn and Ngo when the annual average thunderstorm days equal to 48.5 d.The numbers of the second and the third category lightning protection buildings are more in accordance with the new norm than that of the old norm.According to the new norms,the annual average lightning density is 30% larger than measured value.