ABSTRACT
Most structures can experience several earthquakes throughout their service life. The occurrence of multiple seismic events can lead to incremental structural damage that can increase the structural vulnerability of the built environment. Therefore, aftershocks could result in significant damage for structures that have been affected by previous seismic excitations. The current literature addresses this problem by modeling the consequences of earthquake occurrences as shock deterioration processes affecting structures over time and ultimately impairing their ability to sustain given demands. Due to the relatively short time over which earthquakes act on structures, the real-time damage accumulation within the event is usually disregarded in favor of simplified procedures that model the total effect of each earthquake as a whole. However, this could lead to overly simplified models that use aggregated measures of intensity of the earthquakes, as opposed to their specific ground motions, and underestimate the actual probabilities of failure. Recently, formulations that use Stochastic Differential Equations (SDEs) to model the effect of deterioration processes have been proposed. Being continuous in nature, these formulations can be used to provide a more accurate analysis of the effect of an earthquake within the seismic event itself. This work uses the aforementioned formulations of deterioration based on SDEs to accurately analyze the real-time damage accumulation within the occurrence of sequences of earthquakes (i.e., a main shock and the following aftershocks.) Models are calibrated based on results from Structural Health Monitoring and Finite Element Analyses. The performance over time of an example structure (expressed in terms of fragility functions) is then estimated using predictions for the main shock-aftershock sequences for a site of interest.
