1. Research Scholar, Dept. of Civil Engineering, National Univ. of Singapore, 1 Engineering Dr. 2, 117576, Singapore.
2. Associate Professor, Dept. of Civil Engineering, National Univ. of Singapore, 1 Engineering Dr. 2, 117576, Singapore (corresponding author).
3. Professor, Dept. of Civil Engineering, Tsinghua Univ., Beijing, 100084, People’s Republic of China.