1. Professor, School of Civil Engineering, Southwest Jiaotong Univ., Chengdu 610031, China (corresponding author).
2. Ph.D. Student, School of Civil Engineering, Southwest Jiaotong Univ., Chengdu 610031, China.
3. Professor, School of Mathematics, Southwest Jiaotong Univ., Chengdu 610031, China.
4. Master Student, School of Civil Engineering, Southwest Jiaotong Univ., Chengdu 610031, China.
5. Professor, School of Civil Engineering, Chongqing Univ., Chongqing 400044, China.