1. Researcher, Faculty of Civil and Geodetic Engineering, Chair of Mechanics, Univ. of Ljubljana, Jamova 2, 1000 Ljubljana, Slovenia.
2. Professor, Faculty of Civil and Geodetic Engineering, Chair of Mechanics, Univ. of Ljubljana, Jamova 2, 1000 Ljubljana, Slovenia.
3. Associate Professor, Faculty of Civil and Geodetic Engineering, Chair of Mechanics, Univ. of Ljubljana, Jamova 2, 1000 Ljubljana, Slovenia (corresponding author).