1. Teaching Assistant, Structural Engineering Dept., Faculty of Engineering, Cairo Univ., Cairo 12613, Egypt.
2. Professor, Structural Engineering Dept., Faculty of Engineering, Cairo Univ., Cairo 12613, Egypt (corresponding author).
3. Research Assistant, Univ. School for Advanced Studies IUSS Pavia, Pavia 27100, Italy.
4. Assistant Professor, School of Civil Engineering, National Technical Univ. of Athens, Athens 15780, Greece.
5. Professor, Structural Engineering Dept., Faculty of Engineering, Cairo Univ., Cairo 12613, Egypt.