Vol.25, No.1, 2025, pp. 27–35
https://doi.org/10.69644/ivk-2025-01-0027  

Fiber reinforced elastomeric isolator (FREI) is a new seismic isolator which has been studied in the world and is expected to be utilised in medium and low-rise buildings. It consists of alternating layers of rubber bonded to fiber layers as reinforcement sheets. FREIs are primarily categorised into two types: bonded fiber reinforced elastomeric isolator (B-FREI) and unbonded fiber reinforced elastomeric isolator (U-FREI). In this study, a base-isolated 5-storey reinforced concrete building supported on FREIs in two cases: using B-FREIs and using U-FREIs under the action of various recorded real earthquake time history ground motions is investigated by finite element analysis using SAP2000 software. Mechanical characteristics of both B-FREIs and U-FREIs are utilised in defining the nonlinear property of the model used for simulating isolators. The force-deformation behaviour of an isolator is modelled as bi-linear hysteretic behaviour which can be effectively used to model all isolation system in practice. Comparison of the dynamic responses of the base-isolated building in two cases shows that the mitigation of seismic vulnerability of the base-isolated building supported on U-FREIs is better than that of the base-isolated building supported on B-FREIs under earthquakes with high values of peak acceleration of ground motions. U-FREIs are recommended for seismic isolation of medium and low-rise buildings.

Keywords: • base isolation • fiber reinforced elastomeric isolator • floor acceleration • inter-storey drift • earthquake