1. Lecturer, College of Civil Engineering, Hunan Univ. of Science and Technology, Xiangtan 411201, China; formerly, Ph.D. Candidate, College of Civil Engineering, Hunan Univ., Changsha 410082, China (corresponding author).
2. Professor and Associate Dept. Chair, Dept. of Civil and Environmental Engineering, Univ. of Michigan, Ann Arbor, MI 48109.
3. Professor of Civil Engineering, College of Civil Engineering, Hunan Univ., Changsha 410082, China; Professor of Civil Engineering, Dept. of Civil Engineering, Univ. of Southern California, Los Angeles, CA 90089.