There are 3 methods to calculate the buckling lengths:
- Non-displaceabable nodes (syn.: non-sway buckling lengths)
- Semi-displaceabable nodes
- Displaceabable nodes (syn.: sway buckling lengths)
The prefered method depends on the sway or non-sway character of the building and if global imperfections have been taken into account.
The diagram below gives an overview. The red paths are possible in Diamonds. The ‘*’ means that instead of non-sway buckling lengths, you may also use the semi-displaceable nodes as a conservative alternative.