1. Dept. of Civ. and Struct. Engrg., Hong Kong Polytechnic Univ., Hung Hom, Kowloon, Hong Kong, China. E-mail: cejhyin@polyu.edu.hk
2. Dept. of Civ. and Struct. Engrg., Hong Kong Polytechnic Univ., Hung Hom, Kowloon, Hong Kong, China.
3. Dept. of Civ. Engrg. and Appl. Mech., McGill Univ., Montreal, PQ, Canada H3A 2K6. E-mail: apss@civil.lan.mcgill.ca