1. Faculty of Engineering, Alexandria Univ., Alexandria, Egypt,
2. Associate Professor, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, Urbana, IL 61801 (corresponding author).
3. Associate Professor, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, Urbana, IL 61801.
4. Associate Research Scientist, Dept. of Civil Engineering and Engineering Mechanics, Columbia Univ., NY, NY 10027.