Interaktion mellan axiell normalkraft och böjmoment enligt Eurokod 3:Dimensionering av stålkonstruktioner : En undersökning kring hur samtidig normalkraft och böjmoment hanteras enligt normerna, dess användbarhet samt skillnader

Sammanfattning: Below in the report, the various methods available to calculate the interaction formulas for bending moment and normal force in steel columns are examined. The standards compared are SS-EN 1993-1-1:2005 Annex A, SS-EN 1993-1-1:2005 Annex B, SS-EN 1993-1-1:2022, CEN/TS 1993-1- 101:2022 and Fpr EN 1993-1-3:2023. When calculating and comparing, the results show that the methods are similar to each other as below: SS-EN 1993-1-1:2005 Annex A and CEN/TS 1993-1-101:2022 SS-EN 1993-1-1:2005 Annex B and SS-EN 1993-1-1:2022 In Fpr EN 1993-1-3:2023 - General rules - Supplementary rules for cold-formed members and sheeting, a method is given that can also be used for hot-rolled and welded cross-sections, this method has similarities with the one previously used in BSK07. The result shows that the method gives quick results, but which gives a utilization rate about 10 percentage points higher than the other methods for this calculation case. Hence, the group finds it difficult to justify the use of this method with regard to the material consumption compared to other methods. In the case of a welded cross-section with the same moment of inertia in the rigid direction as a hot-formed steel profile HEA180, the result shows a greater spread of utilization rates between the methods. The result shows that the similarities between the methods follow the same pattern as above. The group has identified the reduction factor regarding lateral torsional buckling and its calculation process is what generates differences between the methods. To gain insight into how user-friendly the different calculation methods are, the group has used calculation data from a course in steel construction certification where the course participants are asked to calculate the utilization rate of a column in a hall building and provide comments on the relevant regulations. The group has also done its own survey where the participants would choose one of the four regulations above and perform similar calculations, grade the usability and give short comments on their thoughts on the calculations. Furthermore, the calculations have also been compared with analysis in FEM design, where we can also see that the analysis carried out using SS-EN 1993-1-1:2005 Annex A corresponded with the calculations using the SS-EN 1993-1-1 methods: 2005 Annex A and CEN/TS 1993-1-101:2022. The analysis carried out using SS-EN 1993-1-1:2005 Appendix B as a basis also corresponded with the calculations using the methods SS-EN 1993-1-1:2005 Appendix B and SS-EN 1993-1-1:2022. It can be seen in the surveys that the methods are complicated and that those who participated in the study get different results depending on the choices made and that the equations are complex and require many calculations, which increases the risk of errors. The comments from the surveys show that the participants' opinion generally agrees with the group's own conclusions regarding the difficulities and choices regarding the calculations. With regard to the calculations and comparisons between the methods, the group finds it difficult to justify the choice of a particular calculation method as they are very similar but at the same time have their shortcomings. The group believes that one should carry out more thorough investigations that take into account more load cases, end conditions and cross-sectional shapes if one intends to hopefully find an optimal method.