1. Professor of Civil Engineering, Department of Civil Engineering, Southwest Jiaotong University, Chengdu, P. R. China
2. PhD student of Civil Engineering, Department of Civil Engineering, Southwest Jiaotong University, Chengdu, P. R. China
3. Associate Professor of Civil Engineering, Department of Civil Engineering, Southwest Jiaotong University, Chengdu, P. R. China (corresponding author: )