分析带金属板结构的建筑物内部雷电脉冲磁场分布的等效电路法

提出了一种计算带有非铁磁性金属平板结构建筑物内部雷电脉冲磁场的等效电路法.首先对结构内的金属平板进行网格分割;然后根据电流趋肤效应,用双指数函数拟合平板内部沿厚度的电流分布;接着通过变换电场积分方程,将金属平板转换成等效电路网络.将平板的电路模型与框架的电路模型相结合,通过解电路方程得到金属平板结构上的电流分布,进而计算框架内的雷电脉冲磁场.该方法的有效性通过和边界元法进行比对得到了验证.最后,对一幢装有金属平板的大楼内部的雷电磁场进行了计算,分析了金属平板对雷电脉冲磁场的屏蔽作用.

An Equivalent Circuit Method for Computing Lightning-Induced Magnetic Fields in Structures with Metallic Plates

An equivalent circuit method was presented to calculate lightning-induced magnetic fields in a metallic structure with non-ferromagnetic plates. With this method, thin plates in the structure were divided into tangential elements. According to the skin effect, a double exponential equation was used to simulate the current distribution across the thickness. By the transformation of electric field integral equation, the plates were modeled as interconnected and coupled circuit. By combining the equivalent circuit model of plate and columns, the current distribution on the metallic structure were then solved with a circuit analysis technique. The resultant magnetic field was calculated with the Biot-Savart law. The proposed approach was compared with the numerical method of boundary element method (BEM) and validated by an experiment conducted in the lab. A good agreement among these results was found. Finally the proposed method was used to evaluate the lightning-induced magnetic field in a building equipped with plates. The shielding effect of plates was analyzed.