We have several RSTAB models where effective lengths are assigned to members, however the lateral torsional buckling checks are not performed for all the members.
The first image shows the model being rendered based on the effective lengths. It can be seen that the highlighted region all shares the same effective length and the section is defined as an I-section.
The second image is of the same view showing the utilization for lateral torsional buckling. This check is only being performed for a single member.
Why are the results like this? My expectation is that the lateral torsional buckling check should be performed for all the relevant members.
Please let me know if there is any other information required which may shed light on this or be required to answer the question.
if you can share the model file(without results or FE mesh), that’s enough — I can check directly why LTB is only performed for one member. You can attach it here in the Community or send it to me via private message.
Warping continuity: By default, warping is not transferred across member ends. For continuous beams, create a Member Set so warping is continuous.
Restraints/stiffness: Use member transverse stiffeners (e.g., end plates → automatic warping spring) to model lateral/rotational restraint realistically.
Load application point: 7-DOF applies loads in the centroid; use eccentricity if the load acts at the flange (or define rigid offsets/eccentrically).
Imperfections from eigenmode: Run Stability, scale the eigenmode as imperfection; near the bifurcation load consider 3rd-order theory for accurate internal forces.
Design configuration: For stability use γM1; if torsion exceeds limits, a von Mises stress check with 7-DOF forces is performed. (Plastic design with 7-DOF forces is currently not available.)
If the checklist fixes it, great — otherwise I’ll pinpoint the exact trigger once I have your model.
