1. Engineer, Weidlinger Associates, Inc., 27 Wormwood St., Suite 200, Boston, MA 02210.
2. Project Manager, ARCO Murray National Construction Company, 3110 Woodcreek Dr., Downers Grove, IL 60515.
3. Associate Professor, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, 205 North Mathews Ave., Urbana, IL 61801 (corresponding author).