This option defines the buckling length of bars. It is available after clicking the appropriate icon (for the direction Y or Z) in the Buckling Length Coefficient field in the Member Definition - Parameters dialog.
The coefficient for calculating the buckling length is entered automatically after selecting one of the icons with the appropriate bar end supports. If you want to eliminate the buckling effects from the calculations, you must click 
. This means that buckling will be ignored in the calculations.
Below, there is a group of options concerned with verifying complex bar buckling (CB 71 Code, Article 4,934-2). For a complex bar, it is necessary to verify the buckling of 1 or 2 of its branches between battens.
From the Connection type list, you can select the following:
- Bolts: Le= 1,30 x Lo; whereas, batten length = (difference of batten coordinates x 0,9)
- Clamps: Le= 1,25 x Lo; whereas, batten length = (difference of batten coordinates x 0,9)
- Nails: Le= 1,20 x Lo; whereas, batten length = (difference of batten coordinates x 0,8).
In the Batten coordinates field, you specify the coordinates of the battens on a bar. (This option works same as the internal bracing option). The coordinates can be defined as real or relative (with respect to the bar length) coordinates.