The generalized buckling analysis is applied when the analysis of elastic instabilities (made, for example, with Eurocode 3 norm) is not satisfactory to check the stability of complex assemblies (like cranes or complex electricity pylons). By using such analysis, the engineer can predict the critical load at which buckling failure can occur.
So, at the end of this analysis with Advance Design you’ll get a coefficient of performance of the critical load – lambda coefficient (in fact, it is the ratio of the buckling loads to the currently applied loads) and the efforts state for each buckling Eigen mode.
Please follow the below steps in order to perform such analysis:
- create a new calculation assumption “Generalized buckling” (step 1 from the attached picture);
- select the load case(s)/load combination(s) which can generate elastic instability to the structure and define the number of vibration modes (maximum number of vibration modes is given by the model degrees of freedom) – see the step 2 from the attached picture;
- after performing the FEA, the critical load is obtained for the smaller lambda value – see step 3 from the attached image. If the lambda value is smaller than 10, then the 2nd order effects must be taken into account.
Because buckling can leads to bad or even catastrophic results, Eurocode 3 recommends to perform a second order effect analysis if a factor, “alpha.cr”, is smaller than 10 (see chapter 5.2.1 from EN 1993-1-1). This is, in fact, the relationship between generalized buckling analysis and Eurocode 3. “Lambda” coefficient, determined by Advance Design, has the same meaning as “alpha.cr” coefficient, mentioned in EN 1993-1-1.
Some theoretical background regarding the generalized buckling analysis can be found in the Advance Design “Validation Guide” document (please refer to chapters 1.10, 1.64, 1.92). For each Advance Design version it can be downloaded from your Advantages account > section Downloads > Documentation > Advance Design or, for the current Advance Design 2014 version you can download it from here.
Attachment: generalized buckling.zip