Measurement of the threshold of community seismic resilience using dynamics-based metrics

Abstract

Two dynamics-based threshold metrics are developed for characterizing seismic resilience of a community. An overdamped single-degree-of-freedom (SDOF) system is employed as an analogy to the physical modeling of the recovery process of a community. Three major intrinsic recovery mechanisms, i.e. long-term socioeconomic development, short-term socioeconomic assistance, robustness of engineering systems, are further clarified. Phase plane method which can characterize system stability straightforwardly is employed on the basis of some slow variables called the governing parameters. Two threshold metrics, i.e. recovery rapidity and recovery distance, are then proposed respectively, based on the observation about the features of phase portraits of dynamic systems treated in two different ways. Recovery angle which exhibits independence from initial conditions of dynamic systems performs well in representing resilience rapidity. Recovery distance quantitatively identifies a tolerance that can indicate if a community will be completely recovered or not under a certain seismic damage. The threshold metrics are believed to comply with the intrinsic physical definition of resilience more seriously.