1. Postdoctoral Research Assistant, Dept. of Civil and Environmental Engineering, Univ. of Virginia, P.O. Box 400742, Charlottesville, VA 22904-4742.
2. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Virginia, P.O. Box 400742, Charlottesville, VA 22904-4742 (corresponding author).
3. Professor, Dept. of Civil and Environmental Engineering, Univ. of Virginia, P.O. Box 400742, Charlottesville, VA 22904-4742.