1. Ph.D. Candidate, Civil Engineering Dept., Univ. of Patras, 265 00 Rio, Greece.
2. Civil Engineer, Langousis Constructions, 80 Spartis and Sfaktirias, 185 46 Piraeus, Greece.
3. Associate Professor, Civil Engineering Dept., Univ. of Patras, 265 00 Rio, Greece (corresponding author). E-mail address: