1. Lecturer, Civil Engineering Dept., Laboratory of Reinforced Concrete and Masonry Structures, Aristotle Univ. of Thessaloniki, Thessaloniki 54124, Greece (corresponding author).
2. Professor, Civil Engineering Dept., Laboratory of Reinforced Concrete, Demokritus Univ. of Thrace, Vas. Sofias 12, Xanthi 67100, Greece; presently, Professor, Dept. of Civil and Environmental Engineering, Univ. of Cyprus, 1678 Nicosia, Cyprus.
3. William J. & Elaine F. Hall Endowed Professor, Civil and Environmental Engineering Dept., Univ. of Illinois at Urbana-Champaign, 2129e Newmark Laboratory, 205 N. Mathews Ave., Urbana, IL 61801.