Fiber reinforced elastomeric isolators for the seismic isolation of bridges

Unbonded fiber reinforced elastomeric isolators (U-FREI) have been proposed as a viable alternative to traditional steel reinforced elastomeric isolators (SREI) for use in low-rise building base isolation systems. The viability of U-FREI for this particular application was confirmed through an extensive evaluation of their lateral response under the condition of no rotational deformations of the loading supports. In order to extend the use of U-FREI to bridge applications the consideration of rotational deformation in the analysis is necessary as it is an important component in bridge isolator design. Currently, no data exists in the literature for investigating the influence of rotational deformation on the lateral response of U-FREI, to the best of authors’ knowledge. Accordingly, an experimental and numerical study was completed on U-FREI to investigate their lateral behaviour under a range of vertical loads and rotational deformations in order to determine their suitability as a seismic isolator for bridges. The lateral stiffness and damping were computed experimentally for different levels of vertical pressure, angles of rotations and lateral deformations. Additionally, the resulting stress and strain state within the isolators under peak deformations was also evaluated numerically via 3D modelling and presented in this study.