1. Professor, Inst. for Structural Mechanics, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum, Germany (corresponding author).
2. Project Engineer, Zerna Ingenieure, Lise-Meitner-Allee 11, 44801 Bochum, Germany; formerly, Professor, Inst. for Structural Mechanics, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum, Germany.
3. Inst. for Structural Mechanics, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum, Germany.