1. Research Assistant, Dept. of Civil, Architectural, and Environmental Engineering, Missouri Univ. of Science and Technology, Rolla, MO 65401; Research Assistant, College of Civil Engineering, Hunan Univ., Changsha 410082, China.
2. Professor, College of Civil Engineering, Hunan Univ., Changsha 410082, China (corresponding author).
3. Associate Professor, Dept. of Civil, Architectural, and Environmental Engineering, Missouri Univ. of Science and Technology, Rolla, MO 65401.