A numerical study on the compressive and rotational behavior of fiber reinforced elastomeric isolators (FREI)

Fiber reinforced elastomeric isolators (FREI) possess unique characteristics relative to traditional steel reinforced elastomeric isolators (SREI). FREI can be classified as either bonded or unbonded according to the connection type employed. An understanding of the behavior of FREI under these loading configurations is needed in order to extend the application of FREI to bridges. The objective of this study is to investigate the response of FREI when vertical and rotational deformations are applied separately as well as in combination. Finite element modeling is carried out on five FREI having the same material properties but possessing different geometrical properties. The mean vertical pressure values employed in this studied are 1, 4.5, 7 and 10MPa, which represent the specified upper and lower limits presented in CAN/CSA-S6 and AASHTO-LRFD. The behavior of the isolators under different angles of rotation is investigated up to a maximum value of 0.05 radians. Results obtained from the finite element model study and values obtained from available closed-form analytical solutions are found to be in excellent agreement. In addition, results show that U-FREI experience lower normal stresses and shear strains in the elastomer and lower strains in the reinforcement relative to B-FREI.