1. Ph.D. Candidate, Dept. of Civil Engineering, Purdue Univ., 550 Stadium Mall Dr., West Lafayette, IN 47907-2051.
2. Assistant Professor, Dept. of Civil Engineering, Middle East Technical Univ., 06800 Ankara, Turkey.
3. Professor, Dept. of Civil Engineering, Middle East Technical Univ., 06800 Ankara, Turkey (corresponding author).
4. Associate Professor, Dept. of Civil Engineering, Middle East Technical Univ., 06531 Ankara, Turkey.
5. Professor, Dept. of Civil Engineering, Middle East Technical Univ., 06800 Ankara, Turkey.