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.
Video: How to model buckling of line bodies in ANSYS
This video illustrates sensitivity to this setting, and suggests 3D modelling when appropriate.