1. Professor, Dept. of Civil Engineering, Univ. of Burgos (Spain), c/Villadiego, s/n, 09001 Burgos, Spain (corresponding author).
2. Professor, Member of the American Concrete Institute, Dept. of Civil Engineering, Univ. of Burgos (Spain), c/Villadiego, s/n, 09001 Burgos, Spain.
3. Professor, Member of the American Concrete Institute, Fellow of the American Concrete Institute, Dept. of Civil Engineering, NED Univ. of Engineering and Technology, Karachi, University Rd., 75270 Karachi, Pakistan.