APPLICATION OF BASE ISOLATION TO A LARGE HOSPITAL IN NAPLES, ITALY

The present paper focuses on the application of base isolation (BI) to a complex multi-storey irregular structure for hospital building that is under construction in the North-East of Naples, in South of Italy. The plan layout of the building is about 144x144m and the total height is about 29m. The assessed structure is thus the largest application of BI in Europe; the building will be tested through in-situ full scale uplift after the construction of the structure is completed. The structural system utilized for the superstructure is a reinforced concrete multi-storey framed system. The building exhibits a large mass eccentricity because of the different height (3 and 8 storeys, respectively) of the two L-shape blocks of the superstructure. The fundamental period of vibration of the fixed base frame is relatively high, i.e. 1.22 sec; the horizontal flexibility of the superstructure apparently reduces the beneficial effects of BI. Nevertheless, the case study demonstrates that BI is an effective strategy to improve the seismic performance also for relatively flexible framed structures both at serviceability and ultimate limit states. The isolation system employed comprises 327 circular-shaped high damping rubber bearings with different diameters (600mm, 650mm and 800mm). The design of the sample BI structure was based on the application of the rules implemented in the Eurocode 8, which are similar to those included in the recent Italian seismic code. Architectural and engineering aspects, including both civil and mechanical works, are also discussed.