BASE ISOLATION SYSTEM SUITABLE FOR MASONRY BUILDINGS

Masonry construction is the most popular and suitable for housing purposes in almost all developing countries. Base isolation in the form of pure friction is the simplest (P-F) among all isolation so far developed which can easily applied to low cost brick masonry buildings. The effect of the earthquake ground motion on the behaviour of isolation system is investigated analytically by using a synthetic accelerogram that is compatible with the design spectrum of IS 1893 (Part 1): 2002 corresponding to the level of maximum considered earthquake in the most severe seismic zone (PGA=0.36g). It is observed that, maximum reduction in spectral acceleration occurs with decrease in coefficient of friction at the cost of increased base sliding displacement. But for structures with Tn 0.2 sec maximum sliding displacement is 50mm for coefficient of friction 0.1. As most of masonry buildings are stiff structures with time period less than 0.2 second the sliding displacement are within plinth projection of 75. Hence P-F isolation is one of the best alternatives for reducing earthquake energy transmission to super structure during strong earthquake leading to lesser damages in masonry buildings.