Design of column bases concerning bending and shear nibs

Abstract: The purpose of the thesis is to find out how to design column bases with conventional methods presented by European standards and codes, but above all from the Steel Construction Institute's handbook on structural joints and compare it with finite element analyses. However, today there are no good instructions for how column bases exposed to multiaxial bending should be designed, where assumptions based on structural mechanics also was compared with computer tools. The hand calculations are made in Excel and are something Northpower Stålhallar AB has requested, which will facilitate their work with design of column bases for VKR profiles placed at the middle, along one side, and at the corner of the plate. Several examples of column bases are touched upon in the work, with different load effects, as well as different dimensions of the column base, to assess how the result is affected. Examples of a dowel's bearing capacity are also treated. Finally, the calculations do not differ significantly from the results of the FE analysis at the smaller dimensions of the column foot, and that difference lies on the safe side with both uniaxial and multiaxial bending, as well as for transverse force capacity. The deviation for multiaxial bending was considerably larger, as the calculations were based on assumptions. The problem is that when bending in two directions, it is uncertain where the pressure resultant is located as the magnitude of the bending moment significantly affects the point of attack, while for uniaxial bending it can always be assumed that it is at the flanges.For the larger dimensions, however, it was the opposite, the FE analysis was on the safe side compared to the manual calculations. This makes the result extremely uncertain. The capacity differs at different dimensions of the column foot. The conclusion is that more calculations need to be made, as only a few were examined in this thesis, but based on these results, it is not appropriate to use manual calculations if it is this uncertain. When using a shear dowel, the tensile force on the anchor rods became significantly lower for the FE analysis, this is assumed to be due to the secondary force Nsec.Ed who can be added for design, which was neglected in the manual calculations.