Seismic isolation elastomeric bearings in buildings and bridges have proven to be a very
effective passive method for reducing earthquake-induced forces by lengthening the period of
vibration of the original fixed base structure in conjunction with increasing the damping ratio.
In the present study, four structures have been investigated using a selected set of actual
strong earthquake time histories at the base. The time histories were scaled using an
appropriate scaling method. The structures rang between two story (stiff) up to eight story
(flexible) superstructures based on stiff soil. The isolation systems are described by ten
different generic nonlinear hysteretic models, which are representative of wide range of
elastomeric isolation systems. A computer program has been developed. It has the capability
to implement the modeling of the various mechanisms of interest. The comparative results
show a comprehensive seismic performance of base isolated structures. Finally, the isolated
structures have been compared with the fixed base structures.