1. Professor, Dept. of Civil Engineering, Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry, Tsinghua Univ., Beijing 100084, China (corresponding author).
2. Ph.D. Candidate, Dept. of Civil Engineering, Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry, Tsinghua Univ., Beijing 100084, China.
3. Professor, Dept. of Civil Engineering, Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry, Tsinghua Univ., Beijing 100084, China.
4. Postdoctoral Scholar, Dept. of Civil Engineering, Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry, Tsinghua Univ., Beijing 100084, China.