Convert IFC objects into native Tekla Structures objects

Tekla Structures
2022
Tekla Structures

Convert IFC objects into native Tekla Structures objects

You can convert most linear IFC reference objects such as beams, columns, braces, plates, slabs, footings and walls into native Tekla Structures objects. Conversion also supports polybeams that have curved sections, and have originally been exported from Tekla Structures, and string, int and double type UDAs. The purpose of converting IFC objects in Tekla Structures is to help in the creation of the structural model and to avoid rework in an early modeling phase.

In IFC object conversion, IFC objects are converted either as items or as extrusions. Conversion as item means that an IFC object is converted as a Tekla Structures item, where the 3D shape defines the geometry of the item. Conversion as extrusion means that an IFC object is converted as a part (column, beam, plate, etc.) that has a profile extruded to create the length of the part.

In IFC object conversion you need to do the following:

  1. Before converting, check that the profiles and units in the IFC reference model are compatible with your environment.
  2. Check the object conversion settings in the IFC object conversion settings dialog box and change them, if needed.
  3. Convert the IFC objects to native Tekla Structures objects. There are two alternative ways available in object conversion:
    • Converting all selected reference model objects at one go using the Convert IFC objects command on the Manage tab.
    • Converting using the IFC object conversion change management. You can also perform an update conversion with a new reference model revision using the change management.

For more information about the profile conversion logic, see section "Profile conversion logic" below. Limitations are listed in section "Limitations in IFC object conversion" below.

Is object conversion always necessary?

In Tekla Structures, reference model objects can be used in a way similar to the native objects, for example, in clash detection, reporting and scheduling. There is no need to have everything as native, because the reference model objects can also be used in many ways. For example, reference model objects can be shown in drawings and they can be listed in reports.

The reference files have the benefit compared to the copied files that the content of the files is automatically updated by the designer of that design discipline.

Check and change the IFC object conversion settings

Before you start converting, check the conversion settings and change them if necessary.

  1. On the File menu, click Settings > IFC object conversion settings.
  2. In the IFC object conversion settings dialog box, check and change the conversion settings:
     
    Create report after conversion Not used any longer. The changes list replaces the report.
    Set handles to top flange

    Set the reference lines of beams to top flange.

    If Set handles to top flange is not selected, the reference lines of beams are located in the middle of the beams.

    This setting is not used for polybeams for better conversion results.

    Convert B-rep object

    Convert B-rep objects into Tekla Structures objects.

    You can select conversion to item and conversion to extrusion separately for concrete material and other material, for example, steel. The selected options are applied to direct conversion and in conversion change management.

    B-rep objects are converted to items, and the items are added to the shape catalog. The items belong to class 996.

    Primary profile mapping Profile name Map profiles primarily by comparing the profile names between the IFC model and Tekla Structures profile catalog.

    Dimensions: Map profiles primarily by comparing the object dimensions.

    If the IFC object converter cannot map profiles with the method you select as primary, it applies the secondary (unselected) method.

    Tolerance Enter values for dimension comparison. The unit of measurement is based on the environment.

    The r value in Tolerance affects only rectangular hollow profiles. It is used to distinguish hot rolled profiles from cold rolled profiles.

  3. Copy properties from the IFC object property sets to be used as user-defined attributes of converted Tekla Structures objects:
    1. Click Add to add a row and enter the name of the IFC property in the Property box.

      Write the IFC property as it is shown in the Inquire dialog box (without the prefix EXTERNAL.).

      Dots (.), underscores (_), and spaces are allowed in the property set name.

    2. Enter the name of the user-defined attribute in the UDA box.

      The maximum length of the user-defined attribute name is 20 characters. The user-defined attribute that you add here must also be included in the objects.inp file. Ensure that the attribute name is unique. Enter the original name of the user-defined attribute. For the following, also the translated name is supported: Profile name, Description, Ifc type (type), Object type, Phase, Material, Finish, Profile, and Name.

      Note that you can copy the Object type property to UDA with ObjectType.

    3. Click Type to select the format of the attribute.

      The possible formats are string, integer or double. The type specifies the IFC property datatype, not the UDA datatype.

  4. Before you convert IFC objects into native Tekla Structures objects, check the profiles and materials to ensure that the conversion will be successful, and map the profiles or material manually in the following way:
    1. Click the Check button.

      Tekla Structures displays any missing profiles or materials on the Missing Profiles and Missing Materials tabs in the Missing Mapping dialog box.

    2. Select an appropriate option in the Tekla Structures profile and Tekla Structures material lists to define a mapping for the missing profiles or materials.

      An IFC part profile name can be mapped with a Tekla Structures profile. The mapping of profiles works for IFC data that has a profile name but does not include enough information for conversion. You can change your mappings later if needed. The maps are used in conversion only if the profiles are not found from Tekla Structures catalogs. The profile conversion follows a certain logic described below.

      Material mapping works for both existing and not found materials.

    3. Click Update Mapping Catalogs and Close.

    You can also open and modify the catalog files in a text editor. To do this, click the Catalog button. When you are done, reopen the IFC object conversion settings to take the new settings in use. The files are located in the \attributes folder under the model folder:

    TeklaStructuresCatalogMaterials.txt contains all materials

    TeklaStructuresCatalogProfiles.txt contains all profiles

    MappedMaterials-default.txt maps the materials

    MappedProfiles-default.txt maps the profiles

  5. Click OK in the IFC object conversion settings dialog box.
    Now you can convert the IFC objects using one of the two available ways.

Convert selected IFC objects at one go

You can convert all imported IFC objects at one go using the current object conversion settings. You need to have at least two or more revisions of the same model.

  1. Open the Reference Models list by clicking the Reference Models button in the side pane.
  2. Click the Add model button, browse for the model in the Add model dialog box, and click Add model again.
  3. In the model, select the objects that you want to convert.
  4. Go to the ribbon, and on the Manage tab, click Convert IFC objects.
    The selected objects are converted on the basis of IFC conversion settings. Conversion is done automatically for objects that have not been converted earlier. Converted IFC object are listed in the changes list at the bottom. Each object is on a row of its own, and cuts are listed hierarchically under the related object.

    • To select objects in model, activate the Select objects in the model check box, and then click an object row. This also selects the related native object.
    • To highlight the object in the changes list and show its details, select the Get selected objects from model check boxes, and then click an object in the model.
    • To zoom to the selected object in the model, select the Zoom to selected check box, and then click a row in the changes list. The Zoom to selected check box is disabled if the Select objects in the model is not selected.
    • To show only changes in the property details list, select the Show only changes check box, and then click a row in the changes list.

      Note that in the property details list, if you by accident remove one of the columns, you can bring it back by right-clicking the column title and selecting the column from the context menu. You can then drag the column to the desired location.

    • The status of an object may be New (green) Changed (yellow), Deleted (red), or Up-to-date (blue or gray, when the conversion change management is reopened), or Error (lilac).
    • The Conversion status column shows the resulting conversion status.
    • The properties of a converted object are listed in the property details list that appears in the side pane when you click an object in the changes list.
  5. You can update an object in the list by changing its conversion status to Conversion and clicking Apply changes.
  6. If the lists disappear, click the following buttons that are only visible when the conversion changes list is active:
    • The Changes list button brings back the changes list.
    • The Property details button brings back the property details list.

Convert IFC objects using conversion change management - first conversion

Object conversion change management provides change detection and change management on object level. Conversion change management is needed in the initial data change management to reduce the challenges in construction projects. Objects are not converted automatically but you need to convert the objects using the conversion changes list.

  1. Open the Reference Models list by clicking the Reference Models button .
  2. Click Add model, browse for the model in the Add model dialog box, and click Add model again.
  3. Double-click the model in the Reference Models list to open it, and then click the Start IFC object conversion change management button .

    The current conversion status is displayed in the changes list and conversion management is activated. The status is based on reference model object physical changes and IFC conversion settings. The properties of a reference object are listed in the property details list that appears separately for each object when you click an object in the changes list.

    Use the Select objects in the model, Get selected objects from model, and Zoom to selected check boxes to review the model and the changes and details lists.

    The reference object status and conversion status logic and colors:

     
    Status Conversion status Color
    New No conversion Green
    Changed Conversion as item or Conversion as extrusion Yellow
    Deleted Conversion as item or Conversion as extrusion Red
    Up-to-date Conversion as item or Conversion as extrusion Blue (gray when the conversion change management is reopened)
    Error No conversion Lilac
  4. Convert objects by selecting the desired object rows, selecting Conversion in the Conversion status column and clicking Apply changes. The conversion is based on conversion settings. You can select multiple objects.
    • After conversion, the conversion status is either Conversion as item or Conversion as extrusion depending on the result of the conversion.
    • B-reps are shown as Surface geometry, parametric profiles as Parametric and arbitrary shapes as Arbitrary. Assembly is also Arbitrary, and so are the reference objects that are selected with the Select objects in assemblies or Select objects in components selection switches.

    • If B-rep (Surface geometry in the Reference type column) conversion is selected, conversion is done as item, if not error.
    • If object is extrusion (Arbitrary or Parametric in the Reference type column), it is converted as extrusion.
    • You can force conversion to be item by selecting Conversion as item. In this case, an extrusion object is also converted as item. The conversion does not check if same shape is already available, meaning new shape will always be created.
    • You can force conversion to be extrusion by selecting Conversion as extrusion. In this case, B-rep is also converted as extrusion, profile is by mapping, or by bounding box if there is no mapping. This conversion result is not always as preferred.
    • If the conversion fails, the result is written to the Conversion status column, and the row color is lilac.
  5. If the lists disappear, click the following buttons that are only visible when the conversion management is active:
    • The Changes list button brings back the changes list.
    • The Property details button brings back the property details list.

Convert IFC objects using conversion change management - update conversion

If a previously converted reference object has changed in a newer reference model revision, you can compare the older and newer revisions of the reference model and update the conversion.

  1. Open the Reference Models list by clicking the Reference Models button in the side pane .
  2. Open the older reference model revision by double-clicking it in the Reference Models list.
  3. Update the reference model with a new revision of the reference model by selecting a new revision file in the File list in the Details section and clicking Modify.
  4. Click the Start IFC object conversion change management button .
  5. Go through the changes:
    • Select the Select objects in the model and Zoom to selected check boxes to see the changed objects clearly in the model.
    • Click the changed row to see detailed changes in property details in the side pane.
  6. You can update previously converted objects partially by selecting the Update check box next to a certain property in the property details pane.
    For example, if you only want to update the profile information, only select the Update check box next to the Profile row in the property details pane.
  7. To convert all objects with changed conversion status, select all rows, change the Conversion status to Conversion and click Apply changes.
    • The objects that have a changed conversion status are converted on the basis of the current IFC object conversion settings.
    • You can update previously converted native model objects based on previous conversion type and settings by selecting Conversion in the Conversion status column. You cannot change the type from extrusion to item, in this case you need to delete the native objects and force conversion.
    • If the reference object status is Deleted, select Conversion and click Apply changes. This removes the native object and the link to the removed reference objects.

Macro for selecting converted IFC objects

The Select Converted Objects BasedOn Ifc Objects Selection macro selects the objects that have been converted to native Tekla Structures objects. You may want to select the converted objects to check the properties of the native Tekla Structures objects, for example. This macro is located in the Applications section of the Applications & components catalog.

Class values

The status of the converted object is reported in the changes list in the Class column. Sometimes the input data in the IFC model is not adequate to successfully create the converted object. The following table explains what the class values mean.

 
Class value IFC object data Converted object description

990

Parametric profile with a name

There is enough information in the IFC model to convert the object successfully.

991

Parametric profile without a name

Tekla Structures determines the name of the object based on the objects profile.

992

Arbitrary profile with a name

The profile of the converted object may be incorrectly rotated because there is no parametrized profile data in the IFC model.

993

Arbitrary profile without a name

The profile of the converted object may be incorrectly rotated because there is no parametrized profile data in the IFC model.

The profile name is set to UNKNOWN.

994

B-rep piece with a name

The profile may be an extrema box due to the lack of profile data in the IFC model.

995

B-rep piece without a name

The profile may be an extrema box due to the lack of profile data in the IFC model.

The profile name is set to UNKNOWN.

996

B-rep piece

The object is converted using the Convert B-rep object option in converter settings.

The converted B-rep object is either an item or a concrete item and is added to the shape catalog.

Example: Convert IFC objects into Tekla Structures objects at one go

In this example, an IFC model is used as a basis for your structural model. The beams and columns are converted into native Tekla Structures objects.

  1. Hide irrelevant IFC layers:
    1. Click the Reference Models button in the side pane.
    2. In the Reference Models list, double-click the reference model to open the details.
    3. Open the Layers list by clicking the down arrow on the right.
    4. Hide the unnecessary layers by clicking the eye button next to the layer.

  2. Select all visible IFC objects.
  3. On the Manage tab on the ribbon, click Convert IFC objects.

    Tekla Structures converts the reference objects.

  4. Check the profiles and materials of the IFC objects and map missing material:
    1. On the File menu, click Settings > IFC object conversion settings.
    2. Click Check.

      Tekla Structures lists the missing profiles and materials.

    3. View the Missing Profiles and Missing Materials tabs.

      Tekla Structures lists a missing reference part material Concrete Block.

    4. Select CONCRETE_UNDEFINED from the list.

    5. Click Update Mapping Catalogs and Close.
    6. Select the Create report after conversion check box.
    7. Click OK in the IFC object conversion settings dialog box.
  5. On the Manage tab, click Convert IFC objects again.

    Tekla Structures converts the objects.

    The Class for all the converted objects is 992. That means that the profile of the converted object may be incorrectly rotated because there is no parametrized profile data in the IFC model.

  6. Check the conversion changes list:
    • Select objects in the changes list to highlight them in the model: Use the buttons Select objects in the model and Zoom to selected.

    • Compare the converted objects with the IFC objects.

    • Use the Inquire object button on the ribbon to view detailed information on objects.

Below is an image of converted beams and columns.

Profile conversion logic in IFC object conversion

You can map an IFC part profile name with a Tekla Structures profile. If a profile is not mapped, Tekla Structures uses a certain logic in converting profiles in the IFC object conversion.

When a parametric profile is used in the IFC model, the I, L, U, C, T, Z, Rectangle and Circular type profiles can be defined parametrically:

 

  1. If the IFC file has been created with Tekla Structures, the original profile name is used.
  2. If a profile with the same name is found from the Tekla Structures profile catalog, that profile will be used.
  3. Otherwise, Tekla Structures checks the parameter values to find a corresponding profile. If found, that will be used.
  4. Otherwise, a default parametric profile is used.

When an arbitrary profile used in the IFC model, the profile shape is defined with polygon:

  1. If the IFC file has been created with Tekla Structures, the original profile name is used.
  2. If the shape is detected and found from Tekla Structures profile catalog, that profile will be used. The shape detection supports the standard types of hot rolled profiles.
  3. Otherwise, a new profile is created based on the description of the arbitrary profile.

When B-rep geometry used in the IFC model, the object is defined with surfaces, and profile geometry information is not available:

  1. If corresponding item exists in Tekla Structures model, it will be used.
  2. Otherwise, a new item will be created and used.

If Conversion as item is used for extrusion type of part, a new item is always created.

Limitations in IFC object conversion

Tekla Structures converts most linear IFC objects to native Tekla Structures objects. However, there are some limitations in the conversion.

Tekla Structures is dependent on the quality of the IFC model, because it uses information available in the model when converting objects.

The following limitations exist in the IFC object conversion:

  • The IFC4.0, IFC4.1, and any newer IFC4 formats are not supported in the IFC object conversion.
  • If the IFC model does not comply with the IFC standard, it might not be converted as expected.
  • Bolts, reinforcement and welds cannot be converted to native Tekla Structures objects.
  • The following physical elements are currently supported: IfcBeam, ifcColumn, ifcMember, ifcPile, ifcFooting, ifcPlate, ifcDiscreteAccessory, ifcSlab, ifcWall, ifcWallStandardCase, ifcRailing and ifcBuildingElementPart.
  • Only SweptSolid, Brep, CSG and Clipping representations are supported.
  • Multiple representations for one object are not supported.
  • Profile offset is not supported.
  • Sometimes, chamfers may be converted incorrectly.
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