1. Associate Professor, School of Civil Engineering, Univ. of Sydney, Sydney, NSW 2006, Australia (corresponding author).
2. Ph.D. Student, School of Civil Engineering, Univ. of Sydney, Sydney, NSW 2006, Australia.
3. Professor, Dept. of Civil and Environmental Engineering, Colorado State Univ., Fort Collins, CO 80523.
4. Professor, School of Civil Engineering, Univ. of Sydney, Sydney, NSW 2006, Australia.