特殊建筑物雷击截收面积计算

Calculation Method of Lightning Equivalent Area of Special Buildings

从计算雷击截收面积的逻辑关系出发,以斜坡类建筑和圆顶形建筑两类特殊建筑为例,通过建立相关模型和数学公式,分析计算应从何位置按照何扩大宽度往外偏移能准确地求出截收面积。对于单檐斜坡类建筑、重檐建筑或古塔,根据房檐到屋脊(塔尖)的水平距离和垂直距离的关系,判断出应该按房檐还是屋脊(塔尖)偏移。对于圆顶形或椭圆顶形建筑,利用建筑屋顶的数学公式,建立了到圆心中轴线距离的数学公式,并对其求导数,得到了导数为0时点的横、纵坐标,此点即为偏移点位置,同时得到了对应的扩大宽度。利用AutoCAD偏移及求面积命令得到截收面积,为防雷设计及雷电灾害风险评估中雷击截收面积的准确计算提供参考。

The offset position and the expanded width, with which the lightning equivalent area is calculated, are analyzed by establishing the related model and mathematical formula, according to the logical relationship of equivalent area calculation, taking the slope-shaped building and dome-shaped building as examples. For the single eaves, the double eaves of ancient buildings or ancient towers, the offset positions should be judged from the relationship of the horizontal distance （L）and the vertical distance （H） between the eaves and roof （top）. For the dome-shaped or elliptical-shaped roof buildings, the mathematical formulas from the outside to the central axis are established by using the formula of the roof model. Then the derivatives of the formulas are evaluated. The coordinates with the derivatives being zero （i. e., offset point positions） and the corresponding expanded widths are obtained. The equivalent areas are gained by the means of offsetting and area calculation with AutoCAD software, which provides reference for the accurate calculation of equivalent areas in lightning protection design and disaster risk assessment.