1. Research Assistant, Institute for Mechanics of Materials and Structures, TU Wien-Vienna Univ. of Technology, Karlsplatz 13/202, A-1040 Vienna, Austria.
2. Associate Professor, Institute for Mechanics of Materials and Structures, TU Wien-Vienna Univ. of Technology, Karlsplatz 13/202, A-1040 Vienna, Austria.
3. Full Professor, Institute for Mechanics of Materials and Structures, TU Wien-Vienna Univ. of Technology, Karlsplatz 13/202, A-1040 Vienna, Austria (corresponding author).