L’isolamento sismico per la protezione di edifici industriali

Recent earthquakes in Italy (L’Aquila, 2009 and particularly Emilia, 2012) have evidenced the high seismic vulnerability of many existing industrial buildings, being designed with rc prefabricated elements, and conforming to isostatic schemes. The lack of connections, often characterizing the structural nodes, and the presence of simply supported members, reduce the lateral resistance system to the one set up by the single column fixed at the base, which acts independently as a SDOF system (for one-level buildings) with no possible redistribution of inertial forces. Retrofit and rebuilding strategies allowing to reduce the intrinsic seismic fragility of this kind of structures need to be found. This article shows how isolation is applied for seismic protection in a new large industrial facility situated in L’Aquila (Italy). The proposed construction system combines the application of lead-rubber isolation devices and multi-directional bearings for base isolation, and the use of a prefabricated system with wet joints for the superstructure, which allows to restore the structural continuity at the internal nodes of the rc frame. The isolation devices filter the seismic action transmitted to the superstructure, which, in itself, has an additional ductility capacity due to the iperstatic frame system obtained. The result is a seismically protected building, exibiting an enhanced seismic performance both as regards the structure and the content, the typical shortcomings of rc prefabricated industrial constructions being removed.