1. Ph.D. Student, School of Civil Engineering, Beijing Jiaotong Univ. Shangyuancun 3, Haidian District, Beijing 100044, PR China.
2. Professor, School of Civil Engineering, Beijing Jiaotong Univ., Shangyuancun 3, Haidian District, Beijing 100044, PR China (corresponding author).
3. Assistant Researcher, Bridge Technology Research Center, Research Institute of Highway, Ministry of Transportation, Beijing 100088, PR China.
4. LUNAM Univ., IFSTTAR, Dépt. Géotechnique, Environnement, Risques Naturels et Sciences de la Terre, SV, F-44341 Bouguenais, France; formerly, Ph.D. Student, Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux, F-75732 Paris Cedex 15, France.