LOW-COST SEISMIC ISOLATION BY RUBBER-SOIL MIXTURE FOR DEVELOPING COUNTRIES: A CASE STUDY OF BHAKTAPUR

Abstract

In this study, an application of rubber soil mix (RSM) as a sustainable and low-cost geotechnical seismic isolation (GSI) technique was explored, wherein RSM prepared from three different soil samples taken from different locations of Bhaktapur were first characterized and then the selected test results combined with those in the literature eventually utilized for numerical (FEM) modelling and parametric analyses of a typical low-to-medium-rise RC building with the depth of RSM layer varied. The research revealed that the optimum moisture content (OMC) of RSM was found higher than the corresponding normal soil while the maximum dry density of RSM decreased. The Young's Modulus of RSM calculated as an average of four plots of stress and strain (loading and unloading at different times) for the three samples was found in the range of 3500-7000 kN/m2. Significantly, the contribution of RSM in reducing the inter-story drift (studied for various local ground motions) was found to be about 20% at 2 ft. depth to above 40% at 10 ft. depth. It is, however, recognized and recommended that the study being the first of its kind in Nepal, the findings may need further validation by future studies, preferably involving shake table experiments.