FAQ 003007 EN

26 April 2019

# I calculated effective lengths for my model with 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 back calculated 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 load summary factors refer to the global structure and not to the local elements. However, it may happen that the structure fails globally for some load branch factors (but fails locally as well (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 buckle. Therefore, it is recommended to use only the effective lengths calculated for both columns.

Again in general: Buckling 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.