1. Faculty of Engineering, Dept. of Civil Engineering, The Hashemite Univ., P. O. Box 330127, Zarqa 13133, Jordan; Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana—Champaign, Urbana, IL 61801 (corresponding author).
2. Professor, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana—Champaign, Urbana, IL 61801.