1. Associate Professor, Dept. of Construction Engineering, The American Univ. in Cairo, 113 Kasr El Aini St., P.O. Box 2511, Cairo 11511, Egypt (corresponding author).
2. Graduate Student, Dept. of Construction Engineering, The American Univ. in Cairo, 113 Kasr El Aini St., P.O. Box 2511, Cairo 11511, Egypt.