A design procedure for seismic isolation retrofit of hospitals tailored to the protection of non-structural components

Conventional design of isolation systems is practically based on the fulfilment of structural requirements. This approach is not suitable for hospitals, which are characterized by a massive presence of earthquake-sensitive non-structural components and technological contents whose integrity is essential in the aftermath of strong seismic events. In the present paper, a simple procedure for the design of sliding isolation systems optimized for the protection of high technological buildings, such as hospitals, is suggested. The preliminary sizing of the isolation devices is guided by the fulfilment of specific performance targets aiming at ensuring the operation of non-structural components for service limit states, in addition to structural integrity of the building at the ultimate states. The proposed procedure is exemplified using as case study the hospital of Lamezia Terme, located in a high seismic prone area in southern Italy. Nonlinear time-history analyses performed on the numerical model of the retrofitted building demonstrated the effectiveness of the procedure, by showing that, for the four design levels established by the Italian Building Code, the adopted solution widely fulfils the performance targets, providing the full operation of the medical complex for frequent and occasional earthquakes and fulfilling the immediate occupancy structural level even for high intensity very rare earthquakes.