The technique of the seismic base isolation (Base Isolation System − BIS) represents an innovative structural control system and, in particular, an important passive control system for seismic protection of structures. This technique has reached a high level of reliability and, as a matter of fact, isolated structures do have an elastic behaviour during the earthquakes, even of high intensity. This reliability is witnessed by the new seismic codes that allows for the use of BIS and provides specific design criteria. In this work, the Base Isolation System for a multi- storey reinforced concrete building, highly irregular in plan, has been considered. The Eurocodes (EC0; EC2; EC8) have been adopted and compared with the new Italian seismic code (NTC 2008). The base isolated structure has been compared to the fixed base structure and the significant benefits that the technique provides on the seismic response of the structure, with significant spin on the costs of the structure, have been highlighted.
