Question:
Why are the imperfections taken into account in RFEM and RSTAB when calculating according to the linear static analysis, even though the definition says that no deformations of structural components are considered according to the linear static analysis?
Answer:
In general, an imperfection describes the incompleteness of a structure or the deviation from an ideal shape caused by the production. There are different ways to simulate an imperfection. In RFEM and RSTAB, imperfections are modeled as equivalent loads. The definition of the equivalent loads is shown in Image 01, and is taken from [1]. The same is described in EC 3 [2]. Since these are the equivalent loads that are dependent on the axial force, they are also considered in the calculation according to the linear static analysis. We recommend managing loads and imperfections in separate load cases. They can be combined with each other in load combinations in an appropriate way. Load cases with pure imperfections have to be categorized as the "Imperfection" action type in General Data of the load cases (see Image 02).
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