1. Ph.D. Candidate, School of Civil Engineering, Beijing Jiaotong Univ., No. 3 Shangyuancun, Haidian District, Beijing 100044, People’s Republic of China.
2. Professor, School of Civil Engineering, Beijing Jiaotong Univ., No. 3 Shangyuancun, Haidian District, Beijing 100044, People’s Republic of China (corresponding author).
3. Assistant Professor, School of Civil Engineering, Xi’an Univ. of Architecture and Technology, No. 13 Yanta Rd., Yanta District, Xi’an, Shaanxi 710055, People’s Republic of China.