Probabilistic seismic fragility assessment of isolated nuclear power plant structure using IDA and MSA methods

Abstract

Seismic isolation is a significant useful technology to protect various infrastructures from earthquake hazards. This manuscript employs the incremental dynamic analysis (IDA) and multiple strip (MSA) analysis methods to study the effectiveness of isolation devices on reducing the damage risk of the isolated nuclear power plant structure. Seismic fragility functions for different performance levels are derived using nonlinear time history analyses of isolated nuclear power plant structures under a series of earthquake ground motions. Four limit states, five performance levels, and the intensity measure are proposed to conduct the seismic fragility of isolated nuclear power plant structures. The results indicate that the deformation coefficient of the isolators is a suitable damage index for evaluating the seismic fragility of the isolated nuclear power plant structure, which has a higher safety compared to the non-isolated structure. The maximum error of the exceeding probabilities obtained by IDA and MSA is about 10%, and the fragility curves of MSA are more conservative than the results of IDA. The results can provide a practical guide for the design of an isolated nuclear power plant structure.