You may encounter an Auto-detect specific warning when working with a structural wall or floor.
Message: The analytical model for the structural element cannot be created by the auto-detect method. If the analytical model is needed, adjust the analytical element or change the tolerance of the analytical model settings.
The error message displays when Revit is not able to create an analytical surface for a structural wall or floor and as a result, the analytical surface is not generated. In this case, the surface boundary is not available via API and not available to transfer to analysis packages. The visible analytical surface can be selected and edited, and is based on the structural face outline.
Issue: This problem can arise when editing the physical model:
- The analytical surface boundary is degenerated to a line or point. For example, the auto-detect mechanism can reduce a floor width if a narrow floor attaches along a wall
- The analytical surface boundary cannot be closed because the structural model sketch contains gaps.
Solution: There are several possible solutions:
- If you do not need the analytical model for further structural analysis, you can disable the Analytical Model parameter in a structural wall or floor properties. The warnings will no longer appear.
- If you need the analytical surface, then verify the boundary sketch line makes a closed loop. Sometimes there are small gaps between a line and an arc which cannot be closed automatically.
- In the case of an analytical floor, you can modify the horizontal alignment of an edge. Select the analytical floor and switch from auto-detect to projection alignment.
- You can change the horizontal tolerance of auto-detect on the Analytical Model tab of the Structural Settings dialog. When the tolerance is smaller than the floor width, it will not be reduced. Remember that the tolerance setting is a global value for the whole analytical model, so the model can be regenerated by the auto-detect mechanism.