1. Assistant Professor, Dept. of Civil Engineering, Hacettepe Univ., Ankara 06800, Turkey (corresponding author).
2. Professor, Dept. of Civil Engineering, Middle East Technical Univ., K2-308, Ankara 06800, Turkey.
3. Professor, Dept. of Civil Engineering, Middle East Technical Univ., K2-307, Ankara 06800, Turkey.
4. Professor, Dept. of Civil Engineering, Middle East Technical Univ., K2-209, Ankara 06800, Turkey.