Seismic fragility curves with unconventional ground motion intensity measures from physics-based simulations

This paper explores the performance of different ground motion intensity measures in observational fragility studies, using damage data from the 2009 L’Aquila earthquake and leveraging physics-based numerical simulations (PBS) to calibrate fragility functions. The dataset included masonry and reinforced concrete (RC) buildings representative of the Italian building stock. The optimality (efficiency, proficiency and practicality) of a wide set of ground motion intensity measures was assessed with two methodologies introduced specifically in this work for such purpose. Results from both methodologies are consistent, highlighting the superior performance of average spectral acceleration, particularly for RC buildings. On the other hand, peak ground acceleration was found to perform well especially for masonry buildings. Among integral intensity measures, Housner intensity emerged as the most effective, while Arias intensity and cumulative absolute velocity displayed weaker correlations with damage. Although based on a single case study, these findings offer initial insights into the optimality of different intensity measures for observational seismic fragility studies and underscore the potential of PBS in enhancing region- and site-specific seismic risk assessments.