Seismic fragility analysis of equipment and structures in a Memphis electric substation

ABSTRACT

This report presents a seimic fragility analysis of equipment structures in an electric substation in Memphis, Tennessee. The eletric subtation selected for this study is substation 21, which is located near several major hospital in downtown Memphis. Substation 21 consists of several major types of equipment and structures, for example, 115/12 kV transformers, oil circuit breakers, and switch structures. The failure of equipment and structures is defined as the state at which a component (an equipment or a structure) fails to perform its function. The capacity corresponding to this damage state is then established. On the other hand, the seismic response of a component is determined by either a response spectral analysis or a static analysis. The uncertainties in seismic response and capacity are quantified to determine the probabilities of failure corresponding to various levels of ground shaking. The results are displayed as fragility curves. From the fragility analysis results, the seismic performance of equipment and structures in a substation can be revealed. For example, 115/12 kV transformers in substation 21 are very vulnerable to earthquakes even with moderate magnitude. The fragility analysis results can also provide the necessary data for evaluating the seismic performance of the entire substation and for performing a reliability analysis of the electric transmission system