1. Research Student, Dept. of Civil Engineering, The Univ. of Hong Kong, Pokfulam Rd., Hong Kong.
2. Associate Professor, Dept. of Civil Engineering, The Univ. of Hong Kong, Pokfulam Rd., Hong Kong (corresponding author).
3. Professor of Structural Engineering and Head, School of Civil, Mining and Environmental Engineering, Univ. of Wollongong, Wollongong, NSW 2522, Australia.