1. Ph.D. Candidate, Dept. of Bridge Engineering, Southwest Jiaotong Univ., Chengdu, Sichuan 610031, China.
2. Lecturer, Dept. of Bridge Engineering, Southwest Jiaotong Univ., Chengdu, Sichuan 610031, China (corresponding author).
3. Professor, Dept. of Bridge Engineering, Southwest Jiaotong Univ., Chengdu, Sichuan 610031, China.
4. Lecturer, School of Civil Engineering, Hunan Univ. of Science and Technology, Xiangtan 411201, China.