Shielding Effect of Building Steel Structures Against Impulse Magnetic Fields Excited by Near-field Lightning Strokes

摘要

A Fortran program based on the method of circuit approach is developed to investigate the transient magnetic field shielding effect of building steel structures, considering the case of a nearby lightning stroke. Experimental validation of the numerical program is carried out on a laboratory scale model. Calculations shown that the shielding factor curve of the building steel structure features a cascade distribution. The effect is to homogenize the magnetic field distribution inside the building. Due to the effect of induced current, shielding factor curve presents a mutation nearby the vertical conductor. Between the conductors, the shielding factor maintains almost stable.