Creating models
Describe the structure and let Dlubal CALC build it in your open RFEM.
Build a portal frame in RFEM: span 12 m, height 5 m, HEA 240 columns, IPE 400 rafter, pinned at the base. Then show me what you created.
Say what a drawing would say
The description that works is the one you would hand a colleague: system, spans, sections, material, supports, loads. Leave one of those out and you get a question rather than an assumption.
Continuous beam over three spans, 6 m each, IPE 330 in S235,
pinned at both ends and on the intermediate supports,
permanent load 8 kN/m and imposed 5 kN/m as separate load cases.
Support conditions are the field people leave out most often, and the one that changes the result most. If you do not say, you will be asked.
Units for parametric sections
Include units with dimensions. A 30 × 45 cm rectangle is equivalent to
300 × 450 mm or 0.3 × 0.45 m. Its section name is R_M1 300/450: the
numbers in the name remain in millimeters. A supplied section name is not
converted to meters. Confirmed form dimensions retain the same physical size.
Check three things before calculating
The axis orientation. After creating geometry the assistant states whether Z points up or down and shows a coordinate with its sign. A mirrored model calculates happily and gives plausible nonsense.
The count. Ask what was created. Members, nodes, supports and load cases are quick to compare against what you described, and much quicker than reading results that came from the wrong structure.
The load cases. They are the second most common source of a wrong result: one combined case where you meant two separate ones changes everything downstream.
When the MCP server supports model binding, a chat keeps its model ID even if you activate another model in RFEM or another chat. Access stops if the bound model is closed. Explicitly identify the intended model when you want to switch.
Building from a photo, drawing or scan
A reconstruction task like this builds a new model by default rather than changing your active one, so it does not overwrite work that has nothing to do with the source you handed it. If your active model is empty, the build just happens there. If it already holds an unrelated structure, you are asked whether to build into it anyway or start a separate model, so the choice stays yours either way.
Rebuilding after a mistake
Say what is wrong and identify the affected model. The available tools determine whether it can be changed in place.
From MCP 1.0.14, restricted model creation only creates a new model. It validates inputs and reads back the chosen Z-axis orientation before writing objects. That tool cannot modify an existing model. Use a suitable permitted capability or edit the model yourself in RFEM. Python execution is disabled by default.
If Dlubal CALC hands you a script to run yourself, run it in RFEM's built-in Python editor. A separately installed dlubal.api of a different build returns wrong values without an error.
Example: "The rafter should be IPE 450, not IPE 400. Change it in the named model if the permitted tools support that. Do not create a second model for it."
If a build needed more than one model, the answer names the model that holds the result and marks the others as test models you can discard. It also says what was changed only to get the calculation through, for example hinges that were removed.
If a detail you asked for could not be created, a scissor hinge for example, the answer lists it as not implemented, with the reason and how to add it in RFEM yourself.
After a geometry change, ask for the coordinates of the moved nodes and the lengths of the members attached to them. A node that did not move leaves an inclined member behind, and that model calculates without any warning.
Objects already written can remain after a failure. Inspect the model and the operation status before requesting another build.
A section suggestion does not authorize replacing the section in the model. For a comparison, ask for the catalog source and the section properties from that same record. Give an explicit change request before applying the selected section and recalculating the modified model.
Where to go next
- Running calculations once the model is right.
- RFEM troubleshooting when a build does not start.