Experimental study on rubber compounds for fiber-reinforced elastomeric isolators

Rubber is the basic material for some structural devices, such as seaport fenders and seismic isolators. In order to seismically isolate a structure, it is possible to interpose between the foundation and the superstructure a rubber device that increases the natural period of the structure. This feature reduces the damaging effect on building due to earthquakes. Several rubber pads typically constitute a seismic isolator interspersed with steel laminas or FRP. In this study, two rubber compounds for high damping elastomeric isolators have been proposed. The first is made of a natural rubber-bromobutyl blend (NR-BIIR), and the second is made of natural rubber and ethylene propylene diene monomer blend (NR-EPDM). They have been characterized through different experimental tests: tensile test, tear-resistance test, compression set, relaxation test, accelerated air oven aging, and hardness measurement. Furthermore, a finite element (FE) cyclic shear test analysis has been performed to evaluate the dynamic shear modulus and damping ratio. The results obtained have shown that the two rubber compounds are suitable for high damping elastomeric isolators.