1. Graduate Research Assistant, School of Civil and Environmental Engineering, Georgia Institute of Technology, 790 Atlantic Dr., Atlanta, GA 30332-0355 (corresponding author).
2. Professor and Associate Chair, School of Civil and Environmental Engineering, Georgia Institute of Technology, 790 Atlantic Dr., Atlanta, GA 30332-0355.
3. Assistant Professor, Dept. of Civil and Environmental Engineering, Rice Univ., 6100 Main St., MS-318, Houston, TX 77005.