1. Ph.D. Research Assistant, Technical Education Faculty, Construction Dept., Firat Univ., Elazig 23000, Turkey; School of Civil Engineering, Beijing Jiaotong Univ., Beijing 100044, China.
2. Professor, School of Civil Engineering, Beijing Jiaotong Univ., Beijing 100044, China (corresponding author).
3. Ph.D. Candidate, School of Civil Engineering, Beijing Jiaotong Univ., Beijing 100044, China.
4. Associate Professor, School of Civil Engineering, Beijing Jiaotong Univ., Beijing 100044, China.