1. Researcher, Dept. of Civil and Environmental Engineering, American Univ. of Beirut, P. O. Box 11-0236, Riad El-Solh, Beirut 1107 2020, Lebanon.
2. Associate Professor, Dept. of Civil and Environmental Engineering, American Univ. of Beirut, P. O. Box 11-0236, Riad El-Solh, Beirut 1107 2020, Lebanon (corresponding author).