1. Lecturer, Dept. of Civil Engineering, King Saud Univ., P.O. Box 800, Riyadh 11421, Saudi Arabia; Ph.D. Student, Dept. of Civil Engineering, Univ. of Birmingham, Birmingham B15 2TT, U.K.
2. Professor, Structural Engineering, Dept. of Civil Engineering, Managing Director, Center of Excellence for Concrete Research and Testing, College of Engineering, King Saud Univ., P.O. Box 800, Riyadh 11421, Saudi Arabia (corresponding author).
3. Senior Lecturer, Dept. of Civil Engineering, Univ. of Birmingham, Birmingham B15 2TT, U.K.
4. Lecturer, Dept. of Civil Engineering, Univ. of Birmingham, Birmingham B15 2TT, U.K.