Investigation On Characteristics Of Lightning Striking On Constructions And Applications In Risk Management

Nowadays prediction methods of lightning frequency still remain in application in the electrical geometry model which is relatively simple. It is thought that lightning striking distance is merely concerned to lightning current amplitude, which neglecting the discharge dispersion of downward leader in the lightning development. It cannot reflect the real lightning stroke characteristics for construction.In this article it introduces a newer calculation for lightning protection attractive volume. Based on the traditional electrical geometric model, the impact of building height and orientation of lightning downward leader to probability of occurrence of lightning is considered. Then starting with attractive volume vertical lightning air terminals, equivalent area can be acquired by integrating angle of lightning downward leader and the density probability function. It is approved that results are grossly consistent for structure height higher than100meters in contrast with recommendation algorithm results raised by Eriksson, CCITT national standard GB50057.On the basis of this prediction we predict the number per year of tall buildings may suffer from lightning. When the building is higher than a certain height, the results obtained in this algorithm show more and more differences with national standard along with the high floors.By comprehensive analysis to lightning accidents in Jiangsu Province from2007to2012, we can find that lightning disaster risk is mainly concerned with factors such as annual number of buildings damaged by lightning, regional GDP and possible impact caused by lightning disasters. Considering the important influence of lightning current in the lightning risk, analysis hierarchy process (short for AHP) is used to analyze lightning disaster risk. Result shows that:qualities of constructions, lightning density and lightning current amplitude have a significant influence on the lightning disaster risk. Combined lightning location data, we develop a simple regional lightning risk assessment model on the basis of ArcGIS platform by emphasizing taking the three factors mentioned above into account. By the conclusion above, we take Jiangsu Province for example to study regional lightning risk. It shows that Nanjing is the highest lightning risk area; other regions like prefecture city in Jiangsu Province are with lower risk, which Coincide with disaster accident statistics mentioned in the National Assembly. The method can better reflect the spatial distribution of regional lightning risk, which can also reasonably realize assessment on lightning disaster risk more efficiently and also have certain directive significance to nowadays lightning disaster risk management.