Multihazard response of unbonded fibre-reinforced elastomeric isolator-isolated structures

Abstract

Unbonded fibre-reinforced elastomeric isolator (UFREI) as laminated elastomeric isolator is a relatively new approach to base-isolation devices with improved efficiency, cost-effectiveness and ease. Base-isolated structures become more susceptible to wind loads due to an increase in the period of the structure, and UFREIs have been found to be effective in mitigating occasional wind loads on isolated structures with the help of supplemental devices. This study investigates the multi-hazard response of benchmark structures isolated using UFREIs and subjected to several hazards over a period of time. Hazard timelines consisting of probable prominent seismic and long-term wind events are generated for the analysis. Since fibre layers in UFREI are flexible in bending, the bond strength demand between elastomer and fibre layer decreases by a huge margin, which delays any delamination failure. Thus, fatigue losses in the elastomer layers are used to characterise the damage induced in the UFREI due to multiple hazards throughout the timeline. Maximum principal strain in elastomer layers at various displacement amplitudes is calculated using finite-element modelling, and it is further used to characterise the fatigue damage in elastomer layers. The final fatigue life of the designed UFREI is predicted using the obtained damage indices.