1. Lecturer, School of Civil Engineering and Architecture, Wuhan Univ. of Technology, Wuhan 430070, China; Research Fellow, Dept. of Civil and Environmental Engineering, National Univ. of Singapore, 1 Engineering Dr. 2, Singapore 117576.
2. Associate Professor, Dept. of Civil and Environmental Engineering, National Univ. of Singapore, 1 Engineering Dr. 2, E1A 07-03, Singapore 117576.
3. Research Fellow, Dept. of Civil and Environmental Engineering, National Univ. of Singapore, 1 Engineering Dr. 2, Singapore 117576 (corresponding author).
4. Lecturer, School of Resource and Civil Engineering, Wuhan Institute of Technology, Wuhan 430073, China.