First of all, a detailed 3D model of a single isolator is implemented into ABAQUS and its hysteretic behavior is numerically analyzed. A preliminary validation is provided assuming as reference some existing experimental data obtained on a standard UFREI subjected to hysteretic cycles.

The proposed UFREI is then identified with a single DOF system constituted by a spring exhibiting softening during a cycle, this latter is quite low and can be disregarded without meaningful errors for structural applications. The identification of the 3D model behavior with a single DOF system (non-linear spring with damping) is mandatory to perform large scale non-linear dynamic analyses on isolated full scale buildings. hardening and a damper acting in parallel, see Figure\ref{image1}. Whilst the 3D detailed model shows some dissipation, i.e. energy dissipation

By means of such identification and in this framework, a 3D FE model of a two-story masonry building and isolated with the proposed UFREIs is analyzed in the non-linear dynamic range, assuming different accelerograms as input data. A Concrete Damage Plasticity (CDP) model is employed to characterize the non-linearity of the masonry material.

From simulations results, it is found how the proposed UFREI is a promising and effective isolation system that can be used in developing countries. In addition, the simplified numerical approach proposed allows for a fast and reliable design of such kind of isolators in real cases.