Study of indoor and outdoor electromagnetic environment of buildings during lightning

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Study of indoor and outdoor electromagnetic environment of buildings during lightning

 

Author: Li, Yui Yan Jenny
Title: Study of indoor and outdoor electromagnetic environment of buildings during lightning
Degree: M.Eng.
Year: 2015
Subject: Electromagnetic measurements.
Lightning.
Tall buildings.
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Building Services Engineering
Pages: x, 106 pages : color illustrations
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2826153
URI: http://theses.lib.polyu.edu.hk/handle/200/8241
Abstract: Nowadays, because of the prevalence of computer networks and electronic equipment in buildings, it is important to raise the awareness of the destructive effect when lightning strike onto buildings. The primary purpose of this study is to determine electromagnetic field of indoor environment for high-rise buildings during direct lightning strike. Moreover, investigation is done to study the outdoor electromagnetic environment and emphasize the safety improvement when different earthing and bonding methods are used, as there is lack of regulations on earthing and bonding practices in Hong Kong.Although there are many methods used for investigating the electromagnetic field of a building, this study is conducted by using computational electromagnetic simulation software named Finite-difference time-domain method (FTDT) as FTDT method is an efficient approach to generate a 3-dimensional building and to assess a building's electromagnetic environment. At this preliminary stage, the current distributions on the building main frame and the electromagnetic fields inside a 33 floors building is assessed. It is found that the pattern of current and electromagnetic field of the building is changing descending the building. And results have shown that the peak change rate of current is large, showing that lighting would have a destructive effect on electronic devices inside the block. Furthermore, it is suggested not to place electronic devices too nearby the pillars as the magnetic field value near the pillars are higher indicated that dangerous zone is mainly around the pillars.Besides, the study has simulated two earthing methods on buildings during direct lightning strike suggested by IEC/TS 60479 named type A and type B arrangement. It has revealed that type B bonding is more efficient in protecting human and animals from getting injured during direct lightning strike on buildings. The simulation is also applied into real case studies in Whampao Garden of Hung Hom, similar result has been obtained in the case application that type B bonding suggested by IEC/TS 60479 is more efficient in life protecting purposes.

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