1. Ph.D. Candidate, Dept. of Civil Engineering, Zhejiang Univ., Hangzhou 310058, China.
2. Professor, Dept. of Civil Engineering, Zhejiang Univ., Hangzhou 310058, China (corresponding author).
3. Lecturer, Faculty of Civil Engineering and Mechanics, Kunming Univ. of Science and Technology, Kunming 650504, China.