1. Postdoctoral Research Assistant, Dept. of Civil Engineering, Washington Univ., St. Louis, MO 63130; formerly, Doctoral Candidate.
2. Professor, Dept. of Civil Engineering, Washington Univ., St. Louis, MO 63130 (corresponding author).
3. Assistant Professor, Dept. of Civil Engineering, Univ. of Southern California, Los Angeles, CA 90089.