1. Structural Engineer, Skidmore, Owings & Merrill LLP, 224 South Michigan Ave., Chicago, IL 60604.
2. Associate Professor, Dept. of Civil and Environmental Engineering, 3546 Engineering Building, Michigan State Univ., East Lansing, MI 48824-1226; and, Dept. of Civil and Environmental Engineering, 3574 Engineering Building, Michigan State Univ., East Lansing, MI 48824-1226 (corresponding author).