Vol.21, No.3, 2021, pp. 229–237
UDC:

Un-bonded fiber reinforced elastomeric isolator (U-FREI) is an improved device for mitigation of the seismic response of low-rise buildings. It is installed directly between substructure and superstructure without any connection at the interfaces. The horizontal load-displacement behaviour of an U-FREI subjected to the simultaneous action of vertical load and cyclic horizontal displacement is nonlinear due to rollover deformation and the horizontal stiffness of the isolator is a function of both vertical load and horizontal displacement. Most existing studies concerning the influence of vertical load on horizontal behaviour of isolators are carried out for scaled models of conventional bonded isolators. In this paper, horizontal behaviour of a prototype U-FREI is investigated under the action of varying vertical loads and cyclic horizontal displacements by finite element (FE) analysis and then the influence of vertical load on the performance of the isolator is evaluated. FE analysis results indicate that the effective horizontal stiffness of the U-FREI decreases with the increase in vertical load at a given amplitude of horizontal displacement.

Keywords: base isolation, un-bonded fiber reinforced elastomeric isolator, rollover deformation, vertical load, horizontal behaviour