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