Low-Cost Base-Isolation System for Seismic Protection of Rural Buildings

Abstract

A simple low-cost friction base-isolation system is examined for its applicability in reducing seismic vulnerability of rural buildings. Four friction isolation interfaces, namely, marble–marble, marble–high-density polyethylene, marble–rubber sheet, and marble–geosynthetic, were studied. The friction properties of these interfaces were studied under static and dynamic conditions for a range of normal loads from 10 to 50 kN. The average coefficients of friction for all of these interfaces except marble–rubber were found to be in the range of 0.05–0.15. The effectiveness of these isolation systems was investigated both analytically and experimentally for a spectrum-compatible ground motion corresponding to the maximum credible earthquake for the most severe earthquake zone according to Indian standards for earthquake-resistant design. The analytical prediction of seismic response of buildings with such isolation was found to be in good agreement (within 19%) with the experimental observation. It was found that for marble–marble and marble–geosynthetic interfaces, more than 50% reduction in absolute response acceleration at the roof level could be achieved in comparison with the response of the fixed-base structure at the cost of increasing relative sliding displacements at the friction interface. However, these relative displacements were well within the commonly adopted plinth projection (75 mm).