1. Ph.D. Candidate, Dept. of Civil and Environmental Engineering, Univ. of Michigan, 2340 G.G. Brown, 2350 Hayward, Ann Arbor, MI 48109.
2. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Michigan, 2340 G.G. Brown, 2350 Hayward, Ann Arbor, MI 48109 (corresponding author).