1. Ph.D. Candidate, Dept. of Civil and Environmental Engineering, Univ. of Michigan, Ann Arbor, MI 48109-2125.
2. Associate Professor, Dept. of Civil & Environmental Engineering, Univ. of Michigan, Ann Arbor, MI 48109-2125 (corresponding author). E-mail: eltawil@umich.edu
3. Professor, Dept. of Civil and Environmental Engineering, Univ. of California, Davis, CA 95616.
4. National Institute of Standards and Technology, Gaithersburg, MD.