1. Ph.D. Candidate, Dept. of Civil Engineering, Univ. of Southern California, 3620 S. Vermont Ave., Los Angeles, CA 90089.
2. Professor, Dept. of Civil Engineering, Univ. of Southern California, 3620 S. Vermont Ave., Los Angeles, CA 90089 (corresponding author).,
3. Professor, Dept. of Civil Engineering, Univ. of Southern California, 3620 S. Vermont Ave., Los Angeles, CA 90089.