Seismic Retrofit of r.c. Buildings with Base Isolation

Seismic isolation is today largely used as a passive mitigation system for seismic actions. While this technique can be easily implemented in new structures, more difficult, whenever possible, is the implementation in existing buildings, which can become a real challenge especially in countries where maintenance of old structures, sometimes of historical importance, is an important issue, like Italy. The use of seismic isolation in existing buildings presents interesting features. Using a base isolation system, the period of vibration can be chosen in order to allow input of low spectral amplitude, so that the superstructure can substantially remain in the elastic range. This possibility allows for limiting or even avoiding the conventional retrofit intervention in the superstructure. In fact, the intervention can be concentrated at the lowest level, while no intervention is necessary in the superstructure, so it is not necessary to …