DXF Import

Product Support
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1

Good afternoon,
I have seen that the software allows importing files in DXF format, and I would like to clarify some doubts regarding this.
As I mentioned in my introduction, I am a Civil Engineering student at the University of Santiago de Chile (USACH), with previous experience in surveying, which is my specialty. At the moment, I am learning about importing CAD models into Dlubal and their correct structural interpretation.

In SAP2000, the procedure I follow is to import the DXF file with all the model lines joined at their ends, so that each element shares common nodes.
I would like to confirm if the same principle applies in RFEM or RSTAB:

  • Is it necessary for all lines to be perfectly connected to each other through common points (nodes)?
  • Or can the program automatically recognize and join the ends of nearby lines when importing the DXF?

I attach reference images to illustrate the type of model I am using. In this practice, I am analyzing a frame, although originally it could have been worked as a Warren or Pratt truss; my intention is to do it as a frame for structural comparison purposes.

I appreciate in advance any guidance or recommendations on best practices when preparing DXF models to import them correctly into Dlubal.

Best regards,
Juan Pablo Olivares Morales
Civil Engineering Student – USACH

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3

Hi Juan Pablo,
Thanks for your great question! :blush:
When importing DXF files into RFEM 6 or RSTAB 9, nodes that are very close to each other can be automatically recognized and merged.
To do that, simply activate the option “Minimize Tolerance in Model” in the import dialog. Once this option is enabled, the program automatically sets all model tolerances to 0.00001 m. That means nodes within this distance are united during import. At the same time, RFEM / RSTAB also takes care of small geometric imperfections – for example:

  • Lines or members that are slightly outside of planes are incorporated into the related surfaces.

  • Very small inclinations are classified as vertical elements.

If you prefer a different precision, you can always adjust the model tolerance manually in the Settings and Options of your model. So even if your CAD lines don’t meet perfectly, RFEM will automatically clean up the geometry for you. Are your questions answered with this, or is there anything still unclear?

You can find additional informations in this article:
KB 1941 | Interface to AutoCAD and DXF File Integration - Part 2/3: Import Features

By the way, the main languages used here in the Dlubal Community are English and German. Since translations can sometimes slightly distort technical details, we kindly ask to post questions in English whenever possible.
Thanks a lot for your understanding! :raising_hands:

Best regards,
Ann-Kathrin Dannwerth