Content

• Concept
• IFC export settings
  • IFC version
  • Object geometry conversion type
  • Conversion of specific analysis objects
  • Save export settings
• Verification of export results

Concept

There are two ways to export structural models:

1. save the entinre model using Save as (ifc file format) command, or
2. save an entire, or a partial model, i.e. selected objects, with the Export to IFC command.

When Save as is applied, the entire structural model is always exported, regardless of what is shown in the active model space when the export process is started.

Regardless of the applied method, the export process is controlled by IFC export settings, which defines how FEM-Design objects should be interpreted in IFC.

IFC export settings

Upon starting one of the 2 methods of exporting FEM-Design model to IFC (Save as, or Export to IFC), an IFC export settings dialog will shop up. Here, one can set the exact settings for exporting the particular model.

IFC version

FEM-Design export supports IFC schema version 2x3 and 4.

IFC2x3 (version: TC1; ISO/PAS 16739:2005; published: 2007-07)

Its most widely implemented subset is the Coordination View (version: 2.0) optimized for sharing building information models among architects, structural engineers and building service (MEP) engineers. This view supports both major geometry representation type of objects: Parametric and BREP.

IFC4 (version: ADD2 TC1; ISO 16739-1:2018; published: 2017-10)

The IFC4 schema is an enhanced version of IFC2x3 in which Coordination View is divided into two subsets for different collaboration purposes:

• Design Transfer View: provides building information models with the support of editing or smartly using construction elements within the limited scope of parametric exchange. An example of a target scenario: architects or structural detailers can further edit, document and detail FEM-Design structural model objects (as parametric beams, columns, slabs, walls, etc. in the native environment of their design software).
• Reference View: suitable for all BIM workflows based on model referencing. The IFC model receiver does not want to edit and use the objects we send parametric in her/his native model, and wants to see our model as a "ghost" to pick, join or just measure its points and edges. The other main purpose of this view is to prevent collisions during design or post-collision check.

The view selection determines which geometry conversion type should be chosen for all objects (see Object geometry conversion type).

Note:

IFC4 is not supported in all applications. Use IFC4 only if the receiver application supports it for the intended and expected purpose and without data loss.

Object geometry conversion type

A representation of all objects' geometry can be set to one of the two geometry conversion types: Parametric and BREP. Selection of the type determines the purpose for which the model should be used (editing or referencing).

Parametric (or Extruded): retains the parameter values of the objects (such as thickness, height, cross-section, reference line, or edge location), so that the IFC receiver can create intelligent objects by building them from their parameters. FEM-Design analysis members typically do not have extra special geometry with solid operations cut, so their parameters describe the same exact geometry created and displayed by FEM-Design.

BREP (Boundary representation): describes the body geometry of objects precisely, but in non-parametric way. Suitable for all BIM workflows based on model referencing.

Although BREP conversion does not store cross-section geometry (polyline) or parameters (sides) for a column, the name and size of the cross-section appear as readable information in several important IFC properties: Type name, Description and Reference.

Both conversion types retain the material and colour assigned to the object geometries. Thus, an object colour at the receiving application can be the same with the surface colour displayed in FEM-Design when it is defined by the Object layer colour or the Change appearance command (Modify). Some IFC receivers does not support colour-retention of body surfaces, and overwrites colours according to their own surface colour-material mapping database.

Conversion of specific analysis objects

Structural objects that have clearly mapped pairs in the IFC schema, are automatically assigned with their IFC type. Some examples:

There are however, objects for which there are several possible IFC conversion pairs for modeling purposes. Then the conversion of these FEM-Design objects should be set in the Conversion ... table in IFC export settings.

When exporting FEM-Design model, the load-bearing function classification (LoadBearing IFC property with True value) is set up automatically for each structural element.

The corresponding Object layer is also exported with the objects. If the Storeys and Axes are defined in the project, they are also exported automatically.

Save export settings

The export settings (including material, cross-section, and Type mappings) can be saved and used for future projects. Saved settings are stored in the following folder:

C:\Users\USERNAME\Documents\Strusoft\FEM-Design 21\templates

Verification of export results

After exporting an IFC model, it is a good idea to check its contents in an IFC model viewer. Several free IFC viewers are available in the Internet for export checks.