1. Research Fellow, School of Civil and Environmental Engineering, The Univ. of New South Wales, Sydney, NSW 2052, Australia.
2. Associate Professor, School of Civil and Environmental Engineering, The Univ. of New South Wales, Sydney, NSW 2052, Australia.
3. Professor, Dept. of Civil Engineering, Univ. of Strathclyde, Glasgow, G4 0NG, UK.
4. Professor, School of Civil and Environmental Engineering, The Univ. of New South Wales, Sydney, NSW 2052, Australia.