1. Research Scholar, Dept. of Earthquake Engineering, Indian Institute Technology Roorkee, Roorkee 247-667, India.
2. Professor and Head, Dept. of Earthquake Engineering, Indian Institute Technology Roorkee, Roorkee 247-667, India (corresponding author).
3. Technical Expert, Norwegian Geotechnical Institute, P.O. Box 3930, Ullevaal Stadion 0806 Oslo, Norway.