I have calculated effective lengths for my model using RSBUCK/RF-STABILITY.Which effective lengths are relevant for further analyzes?


RSBUCK/RF-STABILITY calculates at least one critical load factor or one critical load and an assigned buckling shape. The effective length is then counted back from the critical load (see here ). Since this analysis is not carried out for individual local components, but only for the entire structure, the resulting critical load factors refer to the global structure and not to the local elements. However, it may happen that the structure fails globally (and also locally) for some critical load factors (depending on stiffness and axial force state).

The calculated effective lengths should therefore only be used by the members that buckle in the respective buckling mode. In the case of the global failure of a structure (see example Figure 1), it is thus difficult to draw conclusions regarding the buckling behavior of individual members.

Figure 2 shows a structure where the rear columns are buckling. Therefore, it is recommended to use only the effective lengths calculated for both of these columns.

General summary: Effective lengths from the RSBUCK module are only valid for a structural component in the respective direction if the related buckling shape clearly "bulges" the member in relation to the other in the respective direction. It is clear that the axial forces also have an impact on the results here.


Effective length


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Stability analysis according to the eigenvalue method

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