Analytical approach for determining the effective horizontal stiffness of unbonded fiber reinforced elastomeric isolator

Abstract

      Un-bonded fiber reinforced elastomeric isolator (U-FREI) is relatively new laminated elastomeric isolator which has been studied for last twenty years. It is installed directly between the foundation and superstructure without any connection at the interfaces. Horizontal response of the U-FREI is relatively complicated because there is a part of the isolator that is not in contact with the supports. Effective horizontal stiffness of an isolator is an important parameter in the design for base-isolated building, and is determined from its horizontal response. This paper presents an analytical approach for determining the effective horizontal stiffness of the U-FREI by a math formula and the results of the effective horizontal stiffness of the isolator obtained from the analytical approach are
validated with the results obtained from finite element analysis.