1. Assistant Professor, Dept. of Civil and Environmental Engineering, The Hong Kong Polytechnic Univ., Hung Hom, Kowloon, Hong Kong (corresponding author).
2. Graduate Research Assistant, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, 205 N. Mathews Ave., Urbana, IL 61801.
3. Founder Professor of Engineering, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, 205 N. Mathews Ave., Urbana, IL 61801.