1. Assistant Professor, Dept. of Civil and Construction Engineering, Western Michigan Univ., Kalamazoo, MI 49008-5316 (corresponding author).
2. Clifford C. Furnas Professor of Structural Engineering, Dept. of Civil and Environmental Engineering, State Univ. of New York, Buffalo, NY 14260-4300.
3. Assistant Professor, Dept. of Civil, Architectural and Environmental Engineering, Univ. of Colorado, Boulder, CO 80309.