Urban-scale seismic fragility assessment of RC buildings subjected to L'Aquila earthquake

A damage scenario on a database of Reinforced Concrete (RC) buildings subjected to the 6th April 2009 L'Aquila earthquake is derived from the application of the POST (PushOver on Shear Type models) procedure, a simplified analytical methodology for seismic vulnerability assessment of RC buildings at large scale. Based on the simplified assumption of shear type modelling, POST methodology allows the derivation of the non-linear static behaviour of RC buildings accounting for the influence of infill panels. The seismic capacity is evaluated in terms of spectral intensity measures at different Damage States (DSs) based on the displacement capacity of structural and non-structural elements. DSs and the corresponding displacement thresholds are defined through the interpretation of the observational-based DSs provided by the European Macroseismic Scale EMS-98. Finally, a seismic fragility assessment is carried out, introducing random variables and adopting a Monte Carlo simulation technique. A database of 250 RC buildings located in the Municipality of L'Aquila is considered. The predicted damage scenario is compared with the observed post-earthquake damage collected from post-earthquake emergency survey forms. The influence of certain parameters on the derivation of damage scenarios is investigated, namely the assumptions made regarding the distribution of infill panels within the analysed buildings (i.e., internal partitions) and on spectral shape. The reliability of the adopted simplified analytical procedure and of the assumed mechanical interpretation of damage classification of EMS-98 are validated through the comparison of the predicted and observed percentage of buildings in each DS and distributions of damage to structural components (vertical structures and infill panels)