1. Lecturer, Dept. of Civil and Architectural Engineering, Changsha Railway College, The Central South Univ., Hunan 410075, China; Visiting Scholar, Dept. of Civil and Structural Engineering, The Hong Kong Polytechnic Univ., Hong Kong, China.
2. Professor, Dept. of Civil and Structural Engineering, The Hong Kong Polytechnic Univ., Hung Hom, Kowloon, Hong Kong, China.