Observational Seismic Fragility Models for Unreinforced Masonry Buildings Based on Building‐by‐Building Damage Data From the 2012 Emilia Earthquakes

Over recent decades, Italy has been affected by multiple earthquakes, revealing the significant vulnerability of existing structures. These seismic events have resulted in notable human and economic losses, emphasising the importance of evaluating the impact of one or more seismic events on various building types. Developing fragility models to estimate damage and failure probabilities across seismic intensity levels is essential for assessing risk and predicting damage scenarios. This study investigates the seismic fragility of unreinforced masonry buildings. The fragility assessment is based on data collected through AeDES forms after the 2012 Emilia seismic sequence, provided by the Italian Department of Civil Protection. Damage data were converted to a five-level scale derived from the European Macroseismic Scale EMS-98, and the dataset was supplemented with census data on undamaged buildings, resulting in a total sample of about 110 000 URM buildings. Previously developed attenuation relationships, spatial correlation models and shakemaps—calibrated specifically for the Emilia events—were employed to estimate the spatial ground motion intensity distributions. An ordinal statistical model was used to calibrate fragility functions with various ground motion intensity measures (IMs). Subsequent statistical analyses identified the IMs most strongly correlated with observed damage. Finally, the influence of construction age and number of storeys was incorporated, and the resulting fragility curves were compared with those from existing literature.