1. Associate Professor, Dept. of Civil Engineering, Tsinghua Univ., Beijing 100084, China (corresponding author).
2. Master Student, Dept. of Civil Engineering, Tsinghua Univ., Beijing 100084, China.
3. Senior Lecturer, Dept. of Civil Engineering, Monash Univ., Melbourne, Victoria 3800, Australia.
4. Professor, Dept. of Civil Engineering, Tsinghua Univ., Beijing 100084, China.