1. Formerly, Research Assistant, 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, College of Civil Engineering, Hunan Univ., Changsha, Hunan 410082, China.
4. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Connecticut, Storrs, CT 06269.