1. Dean of The Fu Foundation School of Engineering and Applied Science and Morris A. and Alma Schapiro Professor of Civil Engineering and Engineering Mechanics, Earth and Environmental Engineering, and Computer Science, Columbia Univ., 510 S. W. Mudd Bldg., 500 W. 120th St., New York, NY 10027.
2. Ph.D. Student, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, 205 N. Mathews Ave., Urbana, IL 61801 (corresponding author).
3. Lecturer, School of Built Environment, Univ. of Salford, The Crescent, Salford, Greater Manchester, UK M5 4WT.
4. Associate Professor, Dept. of Civil and Environmental Engineering, Carnegie Mellon Univ., 118 N. Porter Hall, Pittsburgh, PA 15213.
5. Associate Professor, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, 205 N. Mathews Ave., Urbana, IL 61801.