Seismic vulnerability assessment and fragility analysis of industrial RC precast structures

RC precast industrial buildings have recently suffered excessive damage during medium intensity earthquakes, with substantial direct and indirect losses, as highlighted by the seismic events in Northern Italy in May 2012. After an earthquake, the collection of damage data and their inventory represents an essential tool for predicting the response of the buildings to future earthquakes. Therefore, through a critical elaboration of the huge amount of case studies, provided by the 2012 earthquake, the aim of this thesis is to evaluate the seismic fragility of precast reinforced concrete buildings using observational damage data. In order to achieve this goal, it was developed an electronic database to catalog observational damage data related to a wide range of precast RC buildings struck by the Emilia earthquake. The building damages are classified using a six level damage scale derived from EMS-98. The completeness of the database and the spatial distribution of the buildings investigated are analyzed using cadastral data as a reference. The damages of 1890 buildings were related with the epicentral distance and to the peak ground acceleration. Subsequently the damages were examined first, by deriving damage matrices and then estimating empirical fragility curves fitted using Bayesian regression The intensity of the ground motion is quantified by the maximum horizontal peak ground acceleration (PGA), which is estimated for each site from available shakemaps. Subsequently, the precast buildings of the whole damage database have been classified as belonging to a particular type of precast structures. The precast buildings were grouped into seven different typologies and fragility curves were developed for each of them underling the difference in the seismic response.