Empirically based approaches for the derivation of fragility curves of Italian RC building typologies

In this study, fragility curves for Italian RC building typologies are derived, by taking advantage of post-earthquake damage data gathered after the Irpinia (1980) and L'Aquila (2009) seismic events. The severity of the ground shaking is characterized by extrapolating peak ground acceleration values from updated INGV ShakeMaps and a global level of damage, consistently defined with the EMS-98 and accounting for both structural and non-structural damage observed on preselected building components, is associated with each inspected building. RC buildings are allocated to twenty-four building typologies, accounting for construction age, design level and number of storeys. Statistical processing of observational damage data showed the general tendency of seismic vulnerability to increase with the number of storeys and to reduce with design level and construction age. In some cases, the reliability of the obtained results was however affected by the limited amount of damage data and/or by scarcely populated building typologies. Two alternative empirically based approaches, relying on different data processing techniques and fitting strategies, are hence developed, overcoming issues in empirical fragility assessment driven by data paucity and allowing for a robust seismic fragility model.