1. Assistant Professor, Dept. of Civil and Construction Engineering, Oregon State Univ., 101 Kearney Hall, Corvallis, OR 97330 (corresponding author).
2. Professor, Robert L. and Terry L. Bowen Laboratory, Lyles School of Civil Engineering, Purdue Univ., West Lafayette, IN 47907.
3. Engineer, KPFF, 1601 5th Ave. #1600, Seattle, WA 98101.