1. Associate Professor, College of Civil Engineering and Transportation, Hebei Univ. of Technology, Tianjin 300401, China.
2. Postgraduate, College of Civil Engineering and Transportation, Hebei Univ. of Technology, Tianjin 300401, China.
3. Associate Professor, College of Civil Engineering and Transportation, Hebei Univ. of Technology, Tianjin 300401, China (corresponding author).