Abstract

Recent researches on seismic isolated structures are focused on the behaviour of isolation devices when extreme loading conditions are applied, with displacement demands higher than the design value [1]. Generally, the design displacement is considered as the collapse limit and no further capacity is taken into account [2]. This study investigates the effects of the presence of displacement restraints on the response of seismically isolated buildings based on Double Curved Concave Surface Sliders (DCCSS) for displacements larger than the design values. Two residential buildings case studies are considered with moment resistant steel or reinforced concrete frames both isolated with DCCSS [3] [4]. The isolated structures satisfy prescriptions of the current Italian seismic code considering the same seismic actions for the site of L'Aquila. Pushover analyses are carried out in order to estimate the engineering demand parameter (Superstructure Global Drift) limit values used for the definition of the superstructure failure condition. The effects of the impact of the isolation systems against retaining elements on the seismic response of isolated structures are highlighted. The results of multi-stripe analyses using twenty ground motions at ten different seismic intensities [5] are compared.