1. Assistant Professor of Architectural Engineering, Univ. of Nebraska, 203C Peter Kiewit Institute, 1110 South 67th St., Omaha, NE 68182-0681 (corresponding author).
2. Design Engineer, Leslie E. Robertson Associates, R.L.L.P., 30 Broad St., 47th Floor, New York, NY 10004-2304.
3. The Charles J. Vranek Distinguished Professor of Civil Engineering, Univ. of Nebraska, 205E Peter Kiewit Institute, 1110 S. 67th St., Omaha, NE 68182-0681.