A separation-based analytical framework for seismic responses of weakly-coupled electrical equipment

Weakly-coupled electrical equipment, consisting of a series of supporting posts interconnected by flexible connection parts, is commonly seen in power systems. Compared with general structures, weakly-coupled electrical equipment has two main characteristics-(a) the structural integrity of the equipment is weak due to the flexible connection parts and (b) material damping of the supporting posts and connection parts can be very different. Based on these characteristics, global vibration modes and proportional damping should be cautiously used. This restricts applications of common seismic calculation methods for the weakly-coupled equipment. Therefore, the authors developed a separation-based analytical framework for the weakly-coupled electrical equipment, which is presented herein. In this framework, usage of nonproportional damping and local vibration modes of posts and connection parts can be achieved. This framework also facilitated a modeling analysis, which investigate the mechanism of the weakly-coupled effect. It was found that the dynamic transmission of connection parts is the nature of the weakly-coupled effect, and the proportional damping can produce unacceptable errors for the weakly-coupled equipment. To further validate the analytical framework, we conducted shaking table testing on two insulator posts connected by a slidable busbar. The analytical method and conventional mode-superposition method were both employed to calculate the seismic responses of the specimen, and the calculation results were compared with the testing responses. Comparisons suggest the separation-based analytical framework is more applicable and effective for weakly-coupled electrical equipment. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

Weakly-coupled electrical equipment, characterized by flexible connection parts and different material damping, requires cautious consideration of global vibration modes and proportional damping. A separation-based analytical framework was developed to study the mechanism of the weakly-coupled effect, which found that dynamic transmission of the connection parts is the nature of the effect. The framework was proven to be more applicable and effective for weakly-coupled electrical equipment through shaking table testing and comparison with conventional methods.