1. Assistant Professor, Dept. of Civil Engineering, Univ. of Colorado Denver, CO 80222; Lecturer, Dept. of Structural Engineering, Cairo Univ., Giza, Egypt (corresponding author).
2. Professor, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, Urbana, IL 61801.
3. Associate Professor, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana Champaign, Urbana, IL 61801.