Buckling of Line Bodies (Beams) - A Cautionary Note
A model with line bodies that represent beams can have static structural analysis followed by eigenvalue buckling analysis, important for safety.
When beams have open sections such as a C-channel or I-beam, they can be very flexible in torsion. Buckling behavior can be sensitive to whether a warping degree of freedom is added to the beams via an element type KEYOPT command, particularly with shorter beams.
This video illustrates sensitivity to this setting, and suggests 3D modelling when appropriate.