1. Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, 205 N Mathews Ave., Urbana, IL 61801; presently, Major, United States Air Force, Unit 2018 APO, AP 96264 (corresponding author).
2. Professor, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, 205 N Mathews Ave., Urbana, IL 61801.