General Method and Buckling in Plane
Tips & Tricks
The Eurocode 3 implements the General Method for stability analyses. This method is available in a very user-friendly way in the RF‑/STEEL EC3 module. Since the General Method covers only flexural buckling out‑of‑plane and lateral torsional buckling, the question is how to do the design for flexural buckling in plane.
This is usually done by the cross‑section design calculated with internal forces according to the second‑order analysis applying the imperfections. As it is specifically a stability analysis, the resistance must be reduced by the partial safety factor γM1 by selecting the check box ‘Use γM1 for determination of the cross‑section resistance’ in the RF‑/STEEL EC3 module (see Figure). All other stability analyses are then locked, so you need to create a new design case for buckling out‑of‑plane and lateral torsional buckling.
As an alternative, you can use the Equivalent Member Method. The advantage of this method is, that all three stability components are included in one design case. The Equivalent Member Method is suitable for rather simple systems, such as hinge columns or beams with lateral and torsional restraints. For more complex systems, such as with tapered cross‑sections, you have to manually adjust the effective lengths. Although the General Method is better for considering the biaxial bending, it has not yet been officially approved. However, it is already available as an option in RF‑/STEEL EC3.
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