1. Research Engineer, Infrastructure Technology Institute, Northwestern Univ., 2133 Sheridan Rd., Room 1.215, Evanston, IL 60208.
2. Ph.D. Candidate, Dept. of Civil and Environmental Engineering, Northwestern Univ., 2145 Sheridan Rd., Room A320, Evanston, IL 60208.
3. Associate Professor, Dept. of Civil and Environmental Engineering, Northwestern Univ., 2145 Sheridan Rd., Room A332, Evanston, IL 60208 (corresponding author).