Seismic response of a non-symmetric rigid block on a constrained oscillating base

In this paper the influence of base isolation on the behaviour of rigid blocks which represent works of art has been analyzed. The work of art has been modelled with a non-symmetric rigid body, sitting on a base which is connected to a visco-elastic device which represents the passive control system. Two types of security stops have been considered and their effects on the system investigated. The first is able to prevent isolation device breakage by limiting the displacement of the oscillating base to a maximum safety value, the others are introduced to prevent the rigid body from falling off the base. Alternatively the possibility of the rigid block partially coming away from the base was considered. Original equations of motion describing the slide-rocking motion of the rigid block when it is partially outside the support have been obtained. Seismic excitation has been considered by using two registered Italian earthquakes. Collapse due to falling from the oscillating base and due to the overturning of the rigid block has been taken into account. The analysis has been mainly focused on the effects of the friction coefficient, the influence of the slenderness of the body and the role of the two different security stops on the behaviour of the system.