1. Professor, Dept. of Civil Engineering, Laboratory for Earthquake Engineering, National Technical Univ. of Athens, Zografos 15700, Athens, Greece; formerly, Professor, Dept. of Civil Engineering, West Virginia Univ., Morgantown, WV 26506 (corresponding author).
2. Dept. of Civil Engineering, Laboratory for Earthquake Engineering, National Technical Univ. of Athens, Zografos 15700, Athens, Greece.