1. Professor, School of Civil, Environmental and Mining Engineering, Univ. of Adelaide, South Australia 5005, Australia. E-mail: doehlers@civeng.adelaide.edu.au
2. Ph.D. Student, School of Civil, Environmental and Mining Engineering, Univ. of Adelaide, South Australia 5005, Australia.
3. Dept. of Civil and Environmental Engineering, Univ. of Adelaide, Adelaide, SA 5005, Australia.
4. Associate Professor, Dept. of Civil, Construction and Environmental Engineering, North Carolina State University, Raleigh, North Carolina 27695.