System lengths and buckling groups
System lengths and buckling groups is in fact a library dialog in which all the defined buckling groups (BG's) are gathered. It gives the user an overview of all the buckling groups and allows editing of the buckling settings defined in the buckling groups.
It can be accessed either:
- via Libraries > Structure, analysis > System lengths and buckling groups
- via material service (e.g. steel) > Beams > System lengths and buckling groups
Dialog arrangement
The picture bellow displays the dialog of System lengths and buckling groups;
1) List of defined buckling groups
On the left part a list is presented of the defined buckling groups within the project. The list allows multi selection which enables the user to modify common settings at once in that dialog.
For example you can see below a multi-selection of BG1+BG3+BG4 on the left side and on the right side you can see their common properties which can be modified for that selection.
2) Filter for the list of buckling groups
A filter is provided within the dialog that allows to filter the list of defined buckling groups based on either:
- Material (Steel, other - Concrete - Timber - Aluminium)
- Number of parts
- Wildcard name
3) Base settings of selected buckling groups
On the right side of the dialog you can find the base settings of the selected buckling group(s). The composition of the base settings depends on the assigned material in that buckling group.
The content per material is summarized in the following picture:
In the purple rectangle we can see the base settings for concrete while in the orange rectangle we can see the base settings for steel, timber, aluminium.
| Base setting | Explanation |
| Name | Input field for defining the name of the buckling group |
| Number of parts | Displays the number of parts (=maximum number of allowable spans) |
| Description | Input field for adding a description |
| Member(s) material | Displays the material to be used with the buckling group |
| ky factor |
Setting for defining the ky factor determination: - Calculate: buckling factors are calculated (see "Calculation buckling ratio – general formula"for more info) - Factor: buckling factors are manually inputted - Length: buckling lengths are manually inputted - Support (only available for concrete): support conditions (fixed, hinge, free, roll) are manually defined per span - Code dependent (only available for concrete in IBC-code) |
| kz factor |
Setting for defining the ky factor determination: - Calculate: buckling factors are calculated (see "Calculation buckling ratio – general formula"for more info) - Factor: buckling factors are manually inputted - Length: buckling lengths are manually inputted - Support (only available for concrete): support conditions (fixed, hinge, free, roll) are manually defined per span - Code dependent (only available for concrete in IBC-code) |
| Point of load application |
The point of load application defines on which position of the beam the loading is applied. This has an influence for Lateral Torsional Buckling, the following settings are available: - On top: the loading is applied on the top flange - In shear center: the loading is applied on the shear center - On bottom: the loading is applied on the bottom flange - Always destabilising: the loading is always applied on the flange under compression - Always stabilising: the loading is always applied on the flange under tension |
| Mcr |
The critical elastic moment Mcr can be obtained via a calculation or manually inputted depending on the chosen setting: - Calculated: Mcr is calculated - User input: Mcr is manually inputted |
| Bow imperfection e0,y |
The local imperfection or bow imperfection can be taken or not taken into account depending on the chosen setting: - Acc. to code (EN 1993/EN 1995/EN 1999) - Elastic - Acc. to code (EN 1993/EN 1995/EN 1999) - Plastic - Acc. to code (EN 1993/EN 1995/EN 1999) - Elastic if required - Acc. to code (EN 1993/EN 1995/EN 1999) - Plastic if required - Manual input of bow imperfection - No bow imperfection |
| Bow imperfection e0,z |
The local imperfection or bow imperfection can be taken or not taken into account depending on the chosen setting: - Acc. to code (EN 1993/EN 1995/EN 1999) - Elastic - Acc. to code (EN 1993/EN 1995/EN 1999) - Plastic - Acc. to code (EN 1993/EN 1995/EN 1999) - Elastic if required - Acc. to code (EN 1993/EN 1995/EN 1999) - Plastic if required - Manual input of bow imperfection - No bow imperfection |
4) Editing possibilities
At the bottom of the dialog buttons are available for the user which allow editing the content of the list:
- New: creates a new buckling group at the bottom of the list
- Insert: inserts a new buckling group under the current selected buckling group
- Edit: edits the currently selected buckling group in the dialog "System lengths and buckling settings"
- Delete: deletes the currently selected buckling group(s). If the to be deleted buckling group was already assigned to a member it will inform the user about it and ask for confirmation (see the example below).
5) Icons for editing
The available icons are displayed in the picture below.
1) Create a new buckling group
2) Insert a new buckling group below the current selected one
3) Opens the properties of the selected buckling group
4) Copy the selected buckling group
5) Delete the selected buckling group
6) Undo/redo
7) Text output of the selected buckling group
8) Open buckling groups from an already created list
9) Save the current buckling groups into a new list