Life-cycle seismic loss estimation and global sensitivity analysis based on stochastic ground motion modeling

Abstract

The assessment of seismic losses for structural systems through adoption of stochastic ground motion models for characterization of the seismic hazard is the focus of this study. An assembly-based vulnerability methodology is adopted for earthquake loss estimation that uses the nonlinear time–history response of the structure under a given excitation to estimate damages in a detailed, component level. Description of the earthquake acceleration time–history through stochastic ground motion models is considered in this context. The parameters of these models are connected to the regional seismicity characteristics (such as moment magnitude and rupture distance) through predictive relationships. Description of the uncertainty for these characteristics and for the predictive relationships, by appropriate probability distributions, leads then to quantification of the life-cycle seismic losses by its expected value. Because of the complexity of the adopted models, estimation of this expected value through stochastic simulation is suggested and techniques for improvement of computational efficiency are discussed. An innovative global sensitivity analysis is also reviewed, based on advanced stochastic sampling concepts. This analysis aims to identify the importance of each of the uncertain parameters, within the seismic hazard description, towards the overall seismic risk (life-cycle cost). The benefits in terms of detailed, versatile description of seismic risk and the computational challenges of the overall simulation-based, probabilistic framework are extensively discussed. The methodology is illustrated through application to a four-storey moment-frame concrete building for estimation of life-cycle repair cost. Emphasis is placed on the results from the sensitivity analysis for investigating the impact on the estimated repair cost of the ground motion model characteristics and of the fragility features of the different assemblies.