This option is used to define the buckling length of members. It is available after pressing the appropriate icon (for the Y or Z direction) in the Buckling length coefficient field of the Member Definition - Parameters dialog box.
The buckling length coefficient is entered automatically once one of the icons with the appropriate end support conditions is selected. The icons are divided into two groups: the first contains typical (code) methods of supporting the member and the corresponding buckling coefficient values, whereas the other - contains icons for calculating the buckling coefficient for columns of multi-story frames (calculation of the buckling length coefficient for one, three and six adjoining bars). Double-click on one of the icons that represent calculation of the buckling length coefficient (
, 
, 
) results in opening an additional dialog box.
Buckling is always considered in calculations when a compressive force is acting on a member, even if it is negligible in relation to other internal forces. The program does not analyze it on its own if the buckling effects may be disregarded or not. If the user wants to exclude the buckling effects from the calculations, the 
icon must be selected. It means that the buckling will be ignored in the calculation process.
The last icon 
enables members with internal bracings (lateral stiffeners of the analyzed members, limiting the buckling length) to be considered in calculations. After a double-click on this icon, the Internal bracings dialog box appears on screen, which allows defining parameters of lateral stiffeners.