Adaptive post-earthquake reliability assessment of structures subjected to aftershocks

This study presents a methodology for operational time-dependent seismic aftershock risk forecasting as a support for rapid decision-making in a post main-shock environment. This issue is addressed herein by calculating the mean daily rate of exceeding a set of discrete limit states by convolving the associated timedependent fragility curves with the daily aftershock hazard forecasts. Two alternative aftershock occurrence models, namely, the modified Omori???s model (MO) and the Epidemic Type Aftershock Sequence (ETAS) are adopted. The Bayesian updating is used to provide sequence-based parameter estimates for the MO model as well as the ground motion prediction equation. In addition, a new methodology for adaptive time- and eventdependent fragility assessment is explored in this work.As a numerical example, daily forecasts of the aftershock risk are estimated for an equivalent single-degree-of-freedom structure subjected to the L???Aquila 2009 aftershock sequence (central Italy).