1. Lecturer, Dept. of Civil Engineering, Nanjing Tech Univ., Nanjing 211800, China (corresponding author).
2. Professor, Dept. of Civil, Environmental and Geomatic Engineering, Univ. College London, Chadwick Building, Gower St., London WC1E 6BT, UK.
3. Professor, Dept. of Civil Engineering, Southeast Univ., Nanjing 210096, China.