In industrial facilities, evaluating the magnetic fields induced inside reinforced concrete buildings struck by lightning is fundamental to define protection measures. Since carrying out full-wave simulations is not always feasible nor practical daily, we propose a variant of the formula given in the standard IEC 62305-4 to calculate the peak values of the magnetic field strength inside grid-like shields formed by the reinforcing steel bars of the buildings. The formula is complemented by a sparse polynomial chaos expansion (PCE) to take into account various geometrical configurations of the grid-like shields. The PCE can be used independently to extrapolate the peak values from the results of either the formula or another computational method. The error of the formula and the PCE are estimated based on the simulation of the reinforcement of ten full-scale buildings for the first, and using alternative PCEs and Monte Carlo sampling for the second.

中文翻译：

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像栅栏一样的雷电感应磁场：多项式混沌展开式的改进公式

在工业设施中，评估雷电击中钢筋混凝土建筑物内部感应的磁场是定义保护措施的基础。由于每天进行全波模拟并不总是可行，也不可行，因此我们提出了标准IEC 62305-4中给出的公式的一种变体，以计算由钢筋形成的网格状屏蔽内的磁场强度的峰值建筑物的酒吧。该公式辅以稀疏的多项式混沌扩展（PCE），以考虑网格状屏蔽的各种几何构造。PCE可以独立使用，从公式或其他计算方法的结果中推断出峰值。