In this study different approaches and combinations of imperfections using GMNIA of unstiffened plates are examined. The imperfections have a crucial influence for the determination of the load bearing capacity of thin plates. According to EN 1993‐1‐5 Annex C, when using GMNIA, the user can choose between equivalent geometric imperfections and a combination of the geometrical and the structural imperfections. The exact influence of the individual imperfections and their combination on the load bearing behavior has not been conclusive clarified. Furthermore, EN 1993‐1‐5 Annex C does not recommend a suitable residual stress model. This study aims to compare the ultimate loads due to compression loading using different imperfection approaches. Ten different combinations are investigated by using GMNIA. The results show that for larger plate slenderness, many of the ultimate loads are above the Winter‐Curve. The influence of the structural imperfections on the ultimate load is higher than the influence of the geometrical imperfections. An appropriate residual stress model is recommended. The geometrical imperfections should be given as a function of the plate slenderness.

In this study, various approaches to and combinations of imperfections are investigated using geometrically and materially non-linear analysis with imperfections (GMNIA) of unstiffened buckling plates. These imperfections have a decisive influence on load-bearing behaviour during stability failure (plate buckling). When applying GMNIA, the user can opt for either equivalent geometric imperfections or a combination of geometrical and structural imperfections as given in EN 1993-1-5 Annex C. Here, the exact influence of the individual imperfections and their combinations on the load-bearing behaviour is not conclusively clarified. Furthermore, EN 1993-1-5 Annex C does not contain a recommendation for a suitable residual stress model. The aim of this investigation is to compare the ultimate load due to compressive stress using different approaches to imperfections. Six different combinations are analysed using GMNIA. The results make it clear that a variety of ultimate loads lie above the Winter curve for larger related slenderness values, 𝜆 ̅ 𝑝 , and thus lead to non-conservative ultimate loads. In addition, initial recommendations for the required size of the imperfection are given for the application of equivalent geometric imperfections depending upon the related slenderness, 𝜆 ̅ 𝑝 . Applying adjusted equivalent geometric imperfections to square plates under compressive stress achieves very good agreement with the Winter curve in the range relevant to the construction industry.