1. West Pomeranian University of Technology in Szczecin, Faculty of Civil and Environmental Engineering, al. Piastów 50a, 70-311 Szczecin, Poland
2. Optimal Design of Structures Krzysztof Kozieł, ul. Na Piasku 12a, 44-122 Gliwice, Poland
3. Silesian University of Technology, Faculty of Civil Engineering, ul. Akademicka 2A, 44-100 Gliwice, Poland