Thin-walled (cold-formed) members
Software IDEA StatiCa Connection is primarily dedicated to the assessment of connections of hot-rolled members which are not significantly affected by buckling. Geometrically linear and materially non-linear analysis is performed because of its fast and stable calculation. However, this type analysis does not take into account the loss of the stability. If you need to investigate the stability behaviour, performing of a linear buckling analysis can help you to detect dangerous areas and provide a factor for Euler’s bifurcation point.
If you still want to use IDEA StatiCa Connection to check the connection of thin-walled (cold-formed) members and if you are experienced user of the software you have to be careful and use the engineering judgment, then you should:
- Perform linear buckling analysis and carefully evaluate each buckling shape, the first 5 presented buckling shapes might not be enough
- Do not rely on the plasticity of thin-walled members and rather limit the von Mises stress to yield strength or even lower
- Be aware that local buckling which is not taken into account can redistribute internal forces in components differently
- Be aware that stiffness of components may be different due to different failure modes or their combination.
- Be aware that presented checks and detailing of components (e.g. bolts, welds) are following guides for standard members. The code checks of thin-walled members may vary and then the provided checks are not correct.
Generally the IDEA StatiCa Connection can be used for modeling thin-walled (cold-formed) connection behavior but for the whole code check other tools have to be used and the final decision has to be made as a conclusion of several used methods and procedures.
For example, let’s take a look at the following joint:
Even though linear buckling analysis was performed it will not help us to decide if the connection is safe. The model has to be created in a way that we can explore the buckling modes of the connection components (e.g. stiffener, plates, haunches) and decide if the buckling factor of the connection components is greater than the limit value in the code.