Friction base isolation by geotextiles for brick masonry buildings

ABSTRACT: The performance of distributed base isolation using smooth geotextile for seismic protection of masonry buildings was studied. The concept of frictional base isolation is applied to masonry buildings by separating the superstructure from the foundation at plinth level by a sliding friction interface in the form of a nonwoven geotextile–smooth (machine ground) marble. The dynamic friction properties of the masonry–geotextile interface were investigated. The shaking table test was performed on a one-half scale, single storey brick masonry model on a sliding interface for bi-axial earthquake ground motion compatible with the 5% damping design spectrum of the Indian standard code for earthquake-resistant design corresponding to the level of maximum considered earthquake in the most severe seismic zone. It was observed that the use of geotextiles as frictional base isolation was quite effective in mitigating earthquake-induced vibrations. A 65% reduction in absolute response acceleration at the roof level was obtained in comparison with the response of the fixed base structure at the cost of 25 mm peak sliding displacement, which was well within the plinth projection of 75 mm.