1. Assoc. Prof., School of Civ. and Struct. Engrg., Nanyang Technol. Univ., Nanyang Ave., Singapore 639798. E-mail: cjames@ntu.edu.sg
2. PhD Student, School of Civ. and Struct. Engrg., Nanyang Technol. Univ., Nanyang Ave., Singapore 639798. E-mail: pp2906893@ntu.edu.sg