1. Ph.D. Candidate, School of Civil Engineering, National Technical Univ., Athens 10682, Greece.
2. Associate Professor, Dept. of Civil Engineering, Univ. of Patras, 203 Civil Engineering Dept., Univ. of Patras, Rio 26500, Greece (corresponding author).
3. Associate Professor, School of Civil Engineering, National Technical Univ., Athens 10682, Greece.