1. Doctoral Candidate, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana–Champaign, Urbana, IL 61801.
2. Nathan M. and Anne M. Newmark Endowed Chair of Civil Engineering, Univ. of Illinois at Urbana–Champaign, Urbana, IL 61801 (corresponding author).
3. Assistant Professor, Dept. of Civil Engineering, Univ. of Tokyo, Tokyo, Japan.