1. Professor, Dept. of Civil Engineering, Tsinghua Univ., Beijing 100084, China (corresponding author).
2. Associate Professor, College of Civil Engineering, Fuzhou Univ., Fujian Province, Fuzhou 350108, China.
3. Ph.D. Candidate, Dept. of Civil Engineering, Tsinghua Univ., Beijing 100084, China.
4. Professor, Institute for Infrastructure Engineering, Univ. of Western Sydney, Penrith, NSW 2751, Australia.