1. Department of Civil and Environmental Engineering, National University of Singapore, Singapore, Singapore;
2. College of Civil Engineering, Lanzhou University of Technology, P. R. China;
3. School of Civil Engineering, Chongqing University, Chongqing, P.R. China;
4. College of Civil Engineering and Architecture, Hainan University, Haikou, P.R. China;
5. Department of Geophysics, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea