First analysis of the isolated artificial ground for the reconstruction of Castelluccio di Norcia

The seismic events occurred in Central Italy in 2016 caused the collapse of many buildings located in the hamlets closest to the epicentral area. These includes the historic centre of the iconic Castelluccio di Norcia, which was almost destroyed by the strongest shock of 6.5 moment magnitude recorded on the morning of October 30th, 2016. The buildings belonging to the historic town centre were load-bearing masonry structures, which are very sensitive to the combination of horizontal and vertical seismic actions typical of near-fault sites. With the target to rebuilding a new and more resilient historic town centre from the seismic point of view, the possibility of creating an isolated artificial ground was proposed. This consists of a large reinforced concrete slab constituting the foundation base of the new buildings of the historic town centre. In order to restore the profile of the town, the slab is step-shaped. This paper aims to highlight the effects of near-fault earthquakes from a phenomenological point of view by considering a simplified model of a base-isolated masonry structure representative of the Castelluccio village reconstruction project. In particular, the effects produced on the structure by the vertical and horizontal components of the earthquake are studied, using non-linear dynamic analyses with the acceleration time histories recorded at the Castelluccio station in October 2016. The impact of the main design parameters, namely the damping ratios of the superstructure and the vertical stiffness of the isolators, on the system response is investigated in detail.