1. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of California at Berkeley, Berkeley, CA 94720 (corresponding author).
2. Associate, Exponent Consultants, 149 Commonwealth Dr., Menlo Park, CA 94025.
3. Ph.D. Candidate, Dept. of Civil and Environmental Engineering, Univ. of California at Berkeley, Berkeley, CA 94720.
4. Professor, Dept. of Civil and Environmental Engineering, Univ. of California at Berkeley, Berkeley, CA 94720.