Large-scale seismic damage scenario assessment of precast buildings after the May 2012 Emilia earthquake

In May 2012, two strong earthquakes hit the northern Italy revealing the significant seismic vulnerability of precast reinforced concrete structures and causing severe damage and many collapses, and high economic losses. After the lesson learnt from these events, more reliable seismic design criteria have been established for the design of new structures and different approaches have been proposed for the seismic assessment of the existing structures. In this context, the paper presents the results of a first application of the PRESSAFE-disp method, recently proposed by the authors, allowing to define the fragility curves of precast RC buildings at various limit states, including collapse. A stock of 91 precast buildings in the industrial area of San Felice sul Panaro (Modena) was selected as a benchmark case study to verify the reliability of the method in assessing seismic damage scenarios. In particular, with reference to the 2012 seismic ground-motion, two large-scale stochastic models are outlined to predict the number of the buildings collapsed in the area. The first one is based on a Monte Carlo simulation which incorporates the evaluation of the uncertainties, while the second one is a direct simplified calculation. Comparative considerations on the outcomes of the two methods for different seismic intensities are discussed, including the directionality effect of the ground-motion. To test the soundness of the simulations, the results of the two methods are compared with the real data collected through in-situ surveys. The procedures proposed here result, on average, in good agreement with the observed damage scenario. It is worth noting that, due to the inherent simplicity of the methods, they could be implemented to perform scenario-based seismic loss assessments to estimate the financial consequences of an earthquake affecting one or more industrial areas, and to drive the decision-making process for the seismic retrofit of existing precast RC buildings.