1. Assistant Lecturer, Structural Engineering Dept., Faculty of Engineering, Tanta Univ., Tanta 31521, Egypt. E-mail: sanadhaytham@yahoo.com
2. Associate Professor, Structural Engineering Dept., Faculty of Engineering, Tanta Univ., Tanta 31521, Egypt (corresponding author). E-mail: mamammar@yahoo.com
3. Professor, Structural Engineering Dept., Faculty of Engineering, Cairo Univ., Cairo, Egypt.