Seismic vulnerability assessment of masonry building supported by STRP isolators

Abstract

Scrap tire rubber pad (STRP) isolators are made from scrap automobile tires, which are expected to be a low-cost material for earthquake-resistant design of low-to-medium-rise buildings in developing countries. This paper describes the seismic vulnerability of a unbonded STRP (U-STRP) base-isolated masonry building using the finite element method. The three-dimensional model of the U-STRP isolators is placed between the foundation and the building without any bonding between them. As a result, the inertia force of the building is transferred to the foundation through the friction. Two alternative versions of the U-STRP isolator: strip-shaped and square-shaped, are analyzed, which have comparable geometric and stiffness properties. The fidelity of the U-STRP isolator model is confirmed using the numerical analysis and experimental results. The seismic vulnerability of the masonry base-isolated building is determined using the pushover analysis and the fragility curves and then compared to that of the identical fixed-base building. The findings show that masonry buildings with uniformly distributed square-shaped U-STRP isolators suffer low damage and base shear compared to those of the same size of strip-shaped U-STRP isolators. The U-STRP base-isolated masonry building has superior seismic performance to that of an identical fixed-base building, and a square-shaped U-STRP is more effective than the strip-shaped isolator.