1. Assistant Professor, Dept. of Civil and Environmental Engineering, Temple Univ., Philadelphia, PA 19122; formerly, Ph.D. Candidate, Dept. of Civil and Environmental Engineering, Univ. of California, Los Angeles, CA 90095-1593.
2. Associate Professor, Dept. of Civil and Environmental Engineering, Univ. of California at Los Angeles, 5731 Boelter Hall, Los Angeles, CA 90095-1593 (corresponding author).