A Comparative Study on Induced Currents in Steel Reinforced Building Due to a Nearby Lightning Strike to Ground and a Strike to Nearby Elevated Object

Abstract

In the present work a study is carried out to determine the magnitude and nature of the induced current in the steel of a steel reinforced concrete building due to a nearby lightning stroke to ground and strike to nearby elevated objects. A comparison of the two is presented. For the study, buildings of three different heights with number of floors are considered. The vertical down conductor of different heights is considered as nearby elevated object. Lightning channel of length 1 km is employed. Two velocities of propagation of channel current, one equal to velocity of light and another of 1/3 of velocity of light are considered. A current source model for the source is employed for the study. Electromagnetic model is employed and Numerical Electromagnetic Code-2 (NEC-2) is used for the numerical field computations. It is found that when lightning strikes the elevated object which is nearby to the building, induces more currents in steel parts of the building rather than the current due to nearby strike to ground. The height of the elevated object also has significant effect on the magnitude of the induced current.