1. Postgraduate Student, Dept. of Civil & Environmental Engineering, Univ. of Adelaide, Adelaide SA 5005, Australia.
2. Senior Lecturer, Dept. of Civil & Environmental Engineering, Univ. of Adelaide, Adelaide SA 5005, Australia.
3. Associate Professor, Dept. of Civil & Environmental Engineering, Univ. of Adelaide, Adelaide SA 5005, Australia.
4. Professor Emeritus, School of Civil & Environmental Engineering, Cornell Univ., Ithaca, NY 14853-3501 (corresponding author).
5. Research Associate, Dept. of Civil & Environmental Engineering, Univ. of Adelaide, Adelaide SA 5005, Australia.