1. Doctoral Student, College of Civil and Transportation Engineering, Hohai Univ., Nanjing, Jiangsu 210098, P.R. China (corresponding author).
2. Professor, College of Civil and Transportation Engineering, Hohai Univ., Nanjing, Jiangsu 210098, P.R. China.
3. Assoicated Professor, College of Civil and Transportation Engineering, Hohai Univ., Nanjing, Jiangsu 210098, P.R. China.