Seismic isolation retrofit of hospital buildings with focus on non-structural components

Critical facilities with high technological content like hospitals are characterized by a massive presence of earthquake-sensitive non-structural utilities and equipment whose full operation is essential in the aftermath of strong seismic events. The paper deals with several aspects of the design of seismically isolated medical centres with focus on their non-structural components. A simplified design procedure is exemplified using as case study the hospital of Lamezia Terme, located in a high seismic prone area in southern Italy, for which a seismic retrofit intervention with curved surface sliders is proposed. The preliminary sizing of the isolation system is guided by structural and non-structural targets. The protection of utilities and medical equipment requires indeed, at different seismic intensities, very stringent performance limitations, and specific thresholds are formulated to ensure both the structural integrity of the building at the ultimate states and the full operation at the service limit states. Nonlinear time-history analyses performed on the retrofitted building demonstrate the effectiveness of the procedure, by showing that, for the four design levels established by the Italian Building Code, the adopted solution provides the operation of the medical complex for frequent and occasional earthquakes and fulfils the immediate occupancy structural level for high intensity very rare earthquakes.