1. Professor, Dept. of Civil Engineering, Zhejiang Univ., Hangzhou, 310027 Zhejiang, P.R. China.
2. Senior Research Fellow, School of Civil and Environmental Engineering, Univ. of New South Wales, NSW 2052, Australia.
3. Professor, School of Civil and Environmental Engineering, Univ. of New South Wales, NSW 2052, Australia (corresponding author).
4. Professor, School of Civil and Environmental Engineering, Univ. of New South Wales, NSW 2052, Australia.