1. Graduate Student, Dept. of Civil and Environmental Engineering, Louisiana State Univ., Baton Rouge, LA 70803.
2. Associate Professor, Dept. of Civil and Architecture Engineering, Changsha Univ. of Science and Technology, Changsha, Hunan Province 410076, China; and Visiting Scholar, Dept. of Civil and Environmental Engineering, Louisiana State Univ., Baton Rouge, LA 70803.
3. Edwin B. and Norma S. McNeil Distinguished Professor, Dept. of Civil and Environmental Engineering, Louisiana State Univ., Baton Rouge, LA 70803 (corresponding author).