When you want to check the
global buckling behaviour of your structure, it is very straightforward, that first, you will perform a buckling analysis. The results of the analysis are the actual stability loss forms of the structure, and the load levels, on which these stability losses will happen
(so called elastic critical load factors). The elastic critical load factors are calculated for each load combination, and they are being used at the global checks to determine the slenderness and the reduction factors each member. Reducing the cross section resistances with the reduction factors will result the global stability resistance of the structure.
But what can you do, if you want to get a picture about the
local buckling behaviour of a single member of your structure, which is sensitive for local buckling?
The answer is the
convert members to plate function of ConSteel.
Here is a nice example how to check local buckling problems:
1. The initial model is a frame, with segmented tapered members, built from welded I sections, with a relatively high web at the corner regions:
2. Checking the global buckling behaviour of the structure, with a buckling analysis
It seems, that the dominant part of the frame is the corner region. It may worth to see this region how it behaves for local buckling.
The critical load level for the buckling shape is 4,25
3. Use the Convert members-to-plates function on the beam at the corner region:
All eccentricities, supports, and member parameters are kept during the transformation. Good to know, that at the end of the converted members, so called rigid bodies are automatically created. The rigid bodies provides the proper load transfer process between the bar members, and the plates:
4. Check the local buckling behaviour of this part, along with the whole structure, by performing a buckling analysis on this model:
The critical load factor for this local buckling mode is 2,73 (!)
5. Perform some modification on the plate, by adding some stiffeners to the region:
6. And finally, perform a buckling analysis again to see the difference in local buckling behaviour after the changes:
The critical load factor for this local buckling mode is
3,52
7. Repeat the iteration until the desired load factor is reached...