1. Research Student, Dept. of Civil Engineering, Univ. of Moratuwa, Moratuwa 10400, Sri Lanka.
2. Emeritus Professor, Dept. of Civil Engineering, Univ. of Moratuwa, Moratuwa 10400, Sri Lanka (corresponding author).
3. Associate Professor, School of Engineering, RMIT Univ., Melbourne, VIC 3001, Australia.
4. Professor, School of Engineering, RMIT Univ., Melbourne, VIC 3001, Australia.