1. Research Associate, Dept. of Structural and Geotechnical Engineering, Univ. of Rome “La Sapienza,” Via Monte d’Oro 28, 00186 Roma, Italy.
2. University Dozent, Institute for Mechanics of Materials and Structures, Vienna Univ. of Technology, Karlsplatz 13/202, A-1040 Vienna, Austria.
3. Professor, Institute for Mechanics of Materials and Structures, Vienna Univ. of Technology, Karlsplatz 13/202, A-1040 Vienna, Austria.