Please check to see if all sets of members selected for the design are straight sets of members. The equivalent member method is only applicable for straight sets of members with a uniform cross-section, so no taper is applicable, for example. In this case, use the preset General Method.
Check of Sets of Members for Equivalent Member Method
I am designing a set of members using the equivalent member method in RF‑/STEEL EC3, but the calculation fails. The system is unstable, delivering the message "Non-designable - ER055) Zero value of the critical moment on the segment".
What could be the reason?





RFEM and RSTAB models can be saved as 3D glTF models (*.glb and *.glTF formats). View the models in 3D in detail with a 3D viewer from Google or Babylon. Take your VR glasses, such as Oculus, to "walk" through the structure.
You can integrate the 3D glTF models into your own websites using JavaScript according to the instructions (as on the Dlubal website Models to Download): "Easily display interactive 3D models on the web & in AR" .

With the Camera Fly Mode view option, you can fly through your RFEM and RSTAB structure. Control the direction and speed of the flight with your keyboard. Additionally, you can save the flight through your structure as a video.

The direct interface with Revit allows you to update the Revit model according to the changes you have made in RFEM or RSTAB. Depending on the modification, the Revit objects may have to be regenerated (deleting the object and subsequent regeneration). The regeneration is performed on the basis of the RFEM/RSTAB model.
If you want to avoid this regeneration, activate the check box 'Update only materials, thicknesses, and sections'. In this case, only the properties of the objects will be adjusted. Changes different from those in material, surface thickness, and section are, however, not considered in this case.

The reinforcement proposal from RF-/CONCRETE Members can be exported to Revit. The rectangular and circular cross-sections are currently supported.
The reinforcement bars can be modified retroactively in Revit.
Where can I find the update reports for RFEM 5, RSTAB 8, SHAPE-THIN, SHAPE-MASSIVE, RX-TIMBER, CRANEWAY, PLATE-BUCKLING, COMPOSITE-BEAM?
For my NVIDIA graphics card, I need to select between a driver from the "Production Branch" and a "New Feature Branch." Which driver is best suited for RFEM/RSTAB?