• Comparing Structural and Architectural Models

Comparing the Structural and Architectural Models Using IFC and Trace & Reference

Depending on the results of strength analysis and design calculations, the structural engineer may propose changes in the layout, size and profile of structural elements. In addition to the 2D structural documentation set created in various file formats (.PDF, .DWG etc.), ArchiCAD can open 3D structural reference models saved as IFC files. Furthermore the differences between the original and the reference models can be displayed with the so-called Trace & Reference feature in ArchiCAD.

This document goes over the recommended comparison steps between:

• Architectural model (Original)
  The original ArchiCAD model simplified to load-bearing structure (see Partial Structure Display)

and

• Structural model (Reference)
  The imported IFC model that includes the changes made by the structural engineer.

Note: Trace & Reference works only with 2D views of the 3D model, such as Floor Plan, Section and Elevation. This feature allows the comparison of two views/drawings on the same screen.

Recommended Comparison Steps in ArchiCAD

1. Open the Reference IFC model in ArchiCAD (File/ Open).
2. Define a new layer (named for example “Reference” layer; Document/ Layers/ Layer Settings) and assign the model (the imported structural elements) to it.

3. Save the Reference model as .PLN.

4. Open the Original ArchiCAD model.

5. Insert the Reference model as an embedded module into the Original model.
   
   Use the Place Hotlinked Module command (File/ External Content) and browse for the PLN file saved in the 3rd step with Choose Hotlink. The Reference model will be placed on a layer (the default is Model Unit – Module) set at Master Layer.
   To compare the Original to Reference, it is suggested that the inserted module be placed at the same position as the Original (use Drag command, if needed).

6. Define two Layer combinations to separate the layers of the Original model from the layers of the embedded module. For example:

   1. “Original” layer combination:
      Hide Model Unit – Module and Reference layers.
      

   2. “Reference” layer combination:
      Hide all layers and show only Model Unit - Module and Reference layers.
      

7. Define Sections where you would like to check modifications.

8. Define two groups (Folders) for the main project views (stories, sections etc.) in the Organizer (for example Original and Reference view folders).
   

9. Associate the Original and Reference layer combinations to the appropriate views, in View Settings.
   

10. Compare Reference to Original with Trace & Reference. To access its palette, choose Window/ Palettes/ Trace & Reference. Trace & Reference works with two views:

    1. Active:
       The actual model or drawing you are currently working on.

    2. Trace Reference:
       Optionally it is placed on top of or underneath the currently Active content. This acts as a kind of underlay, making it easy to compare multiple model views/drawings on the same screen.

Examples

Let’s see examples of how Trace & Reference works for comparing floor plans and sections of the Original and the Reference models.

Floor Plan

Activate a story view of Original (Active) in the Navigator – View Map. Right-click on the same story view (name) of Reference, and choose Show as Trace Reference. The Reference objects are shown in a particular color (for example in red in the next figure).

Section

Do the same steps as described at Floor Plan to compare the Sections of the two models.

More Information

See more about the functions and the possibilities of Trace & Reference Palette in ArchiCAD Help

PDF Download

• The above article is also available in PDF format: ComparingModels.pdf

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