Mar. 2012, Volume 6, No. 3 (Serial No. 52), pp. 308–321 Journal of Civil Engineering and Architecture, ISSN 1934-7359, USA Base Isolation Seismic Retrofit of a Hospital Building in Italy Massimiliano Ferraioli and Alberto Maria Avossa Department of Civil Engineering, Second University of Naples, via Roma 29, 81031, Aversa, CE, Italy Abstract: The paper deals on a significant retrofit project currently under construction of an existing hospital building in Avellino (Italy). The seismic retrofit was realized by connecting together the first floors of the three existing structures and by creating a unique isolation system composed of high damping rubber bearings and sliding devices. The base isolation is achieved by gradually cutting the building from foundation and installing the isolators at the level of upper edge of the columns. The study allows the verification of the adequacy of the isolation system, showing the benefits of the application of the isolation devices, the limitations and the characteristics of their performance. Key words: Seismic retrofit, base isolation, seismic response. 1. Introduction Most of the existing buildings are vulnerable to earthquakes because they are gravity load designed or are designed with earlier codes to withstand seismic action of low intensity. Many of these constructions with low lateral load resisting capacity are located in high seismic hazard areas and so they represent a significant risk to life during earthquakes, especially because many of them are school or hospital buildings. Recently, a new interest in the application of seismic isolation has been caused by the recent strong Italian earthquakes (Umbria-Marche, 1997; Molise-Puglia, 2002; Abruzzo, 2009) and by the editing of the new Italian Code [1]. In fact, like Eurocode 8 [2, 3], the Italian code contains two chapters devoted to seismic isolation of buildings and bridges respectively, and this had a great effect in order to promote the general application of seismic isolation not only for schools, emergency management centers, hospitals and so on, but also in the field of the ordinary residential and commercial buildings. On the other side, the traditional Corresponding author: Massimiliano Ferraioli, PhD, assistant professor, research fields: structural engineering. E-mail: massimiliano.ferraioli@unina2.it. methods of seismic retrofitting based on the increase of the structural capacity may have problems of convergence. In fact, in general these approaches tend to increase not only strength and ductility, but also lateral stiffness. The consequent period shortening of the structure generally increases the seismic demand except in the case of low-rise buildings that fail in the constant-acceleration region of the response spectrum. It is worth noting that seismic isolation and energy dissipation are certainly convenient also from an economical point of view, especially in the case of strategic structures for which the return period of the design seismic event should be very long and the structure will probably suffer many strong earthquakes during its life time. Seismic isolation appears to be the most appropriate solution, which allows the seismic behaviour of the hospital building to comply the provisions of the Italian Code. The key objective of this paper is to present the base isolation retrofit design of a hospital building in Avellino that will ensure cost-effectiveness of the construction works and high reliability of the structure. DAVID PUBLISHING D