Effect of horizontal loading direction on performance of prototype square unbonded fibre reinforced elastomeric isolator

Summary Unbonded fibre reinforced elastomeric isolator (U-FREI) is lightweight and facilitates easier installation in comparison to conventional steel reinforced elastomeric isolators. Most of the previous studies were focused to investigate the behaviour of scaled models of square U-FREIs in 0° or 45° horizontal loading directions. However, the angle of incidence of earthquake to a structure may be from any directions. This paper presents influence of different loading directions (0°, 15°, 30°, and 45°) on the horizontal response of a sample prototype square U-FREI on the basis of both experimental investigation and three-dimensional finite element analysis. Mechanical properties and deformed configurations of the prototype U-FREI computed using finite element analyses are observed to be in good agreement with those obtained from experimental study. It is further observed that as the loading direction changes from 0° to 45°, the effective horizontal stiffness of U-FREI increases, whereas the damping value decreases. Thus, the seismic performance of U-FREI will also vary depending on the direction of load acting on them.

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