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Create property sets for IFC export

Tekla Structures
Modified: 8 Mar 2024
2024
Tekla Structures

Create property sets for IFC export

You can create property sets from template attributes and user-defined attributes, define properties for the attributes, and bind the Tekla Structures property sets to IFC entities for IFC export. You can save the property sets in property set configuration files.

You can use the default property sets, and you do not need to create any custom property sets if the default property sets work for you. You can also modify the default property sets. In addition, you can import buildingSMART property sets.

When Tekla Structures exports an IFC file, it uses the configuration file you selected in the Property sets list to export property sets with the exported IFC entities. The list of configuration files includes predefined files located in your environment folders and files stored in the \AdditionalPsets folder under the current folder.

The Property set definitions dialog box allows you to add and modify the property sets needed in the IFC export. The property set configuration files that you create, will be visible in both IFC2x3 export and IFC4 export.

Note:

We recommend that you define property sets only in the Property set definitions dialog box instead of modifying the file itself to ensure that the XML configuration files are valid.

(1) The name of the selected property set configuration file. In the list, you can see all the available configuration files stored in your environment folders, and select the desired file. The file is loaded automatically after selection.

Use the Save button to save the changes in the configuration file after you have added or modified the property sets. You can also give a new name for the configuration file and save it. New and modified configuration files are saved in the \AdditionalPsets folder under the current model folder. You can also read configuration files from the following folders:

XS_FIRM

XS_PROJECT

XS_SYSTEM

Use the button to clear the contents of the displayed configuration file and create a new configuration file.

(2) To show in the list only the property sets and properties that you have selected using the Include check box, select Show only included.

(3) Property sets in the current configuration file. You can drag property sets up or down in the list.

(4) Search for a specific property set. The list of property sets might be very long, and the search could be very useful when you want to find and select a specific property set.

(5) Show only the property sets for the selected IFC entities.

(6) Show only the property sets for the selected IFC versions.

(7) To export all property sets and all properties in the list, select the Include check box on the title row for the property set or properties section. To export only the needed property sets and properties for different export purposes, select the check box next to a specific property set or property.

(8) Filters allowing you to further limit for which objects to export the property set. For example, specify a filter to further limit which IfcBeam objects to export the property set for, like for steel beams only.

(9) Command buttons for working with property sets:

Add buildingSMART property sets. The property sets beginning with Pset_ or Qto_ are buildingSMART property sets. The buildingSMART property sets are protected, and you cannot change the IFC entities that they are exported with, or edit the names of the properties they contain. However, you can edit the properties in the buildingSMART property sets, and select to include or exclude them.

Add a property set.

Edit the selected property set.

Delete the selected property set.

Duplicate the selected property set. You can then modify the property set so that the properties are the same but the filtering criteria are different, for example.

(10) Properties in the selected property set. You can drag properties up or down in the list.

(11) To enlarge the property set section or the property section, drag the dialog box divider up or down.

(12) Command buttons for working with properties:

Add a property in the selected property set.

Edit the selected property.

Delete the selected property from the selected property set.

Create a custom IFC property set configuration file

In addition to the default configuration files, you can create custom configuration files.
  1. On the File menu, click Export > IFC or Export > IFC4.
  2. Select <new> from the Property sets list and click the Edit button.

    The Property set definitions dialog box opens.

    You can also create a new configuration file in the Property set definitions dialog box by clicking the button next to the button at the top.

  3. Add the needed property sets.
    For details, see "Add property sets" below.
  4. Enter a name for the configuration file.
  5. Click Save.

    New and modified configuration files are saved in the \AdditionalPsets folder under the current model folder. You can also read configuration files from the following folders:

    XS_FIRM

    XS_PROJECT

    XS_SYSTEM

    Next, add property sets in the configuration file.

Add property sets

You can add both custom property sets and buildingSMART property sets in a configuration file. For example, you can add COGs and start and end points on the part level, and scheduling information on the assembly level.
  1. In the Property set definitions dialog box, open a property set configuration file.
  2. To add a custom property set, in the property set section, click Add property set to this configuration file.
  3. In the Add property set dialog box, enter the property set name and description.

    The property set name may contain any text, including spaces. The maximum length of the property set name is 255 characters. Do not start the property set name with prefixes Pset_ or Qto_, these prefixes are reserved for buildingSMART property sets.

  4. You can use a filter to further limit which objects get exported with a given property set.

    For example, specify a filter to further limit which IfcBeam objects to export the property set for, like for steel beams only.

    Do one of the following:

    • Select an existing filter from the list of filters.
    • Create a new filter: click the Display filter button. In the Object group - IFC property export dialog box, create a filter, set Filter type to IFC property export, and save the filter.
  5. Select the IFC entities for the property set.
    You must select at least one IFC entity.
  6. To save the new property set, click Add.
    Now you can add properties in the new property set, see "Add properties in a property set" below.
  7. To add buildingSMART property sets, click Import buildingSMART property sets.
    For details about adding buildingSMART property sets, see "Add a buildingSMART property set" below.
  8. When you have added all the property sets and properties, click Save to save the current configuration file.
When you have several property sets in the list, you can drag those up or down in the list.

Add properties in a property set

You can add properties in an existing property set.

The buildingSMART property sets are protected, and you cannot add properties in those. Property sets with names beginning with Pset_ or Qto_ are buildingSMART property sets. However, you can modify the properties included in buildingSMART property sets.

  1. Open a property set configuration file in the Property set definitions dialog box.
  2. Select a property set from the property set list, and in the property section, click Add property to this property set.

    In the displayed Add property dialog box, all the default properties are listed. You can search for properties, or use the Group drop-down options to narrow down the list according to the object type.

  3. Click a property to select it.
    When you have selected a property, Name, Tekla property, and Type are filled in automatically.

    You can change the Name of the property. Once you have changed the Name, it no longer changes automatically.

  4. To change the type of the property, click the Type drop-down.

    The Type can be one of the following:

    • String: sequence of characters
    • Boolean: true or false
    • Integer: a whole number
    • Measurement
    • Real: a number that has a decimal representation
    • Time stamp
  5. If you selected Measurement as the type, more settings are displayed:

    Measurement type: Select the appropriate measurement type from the list.

    Conversion: Select the unit conversion factor. The available options depend on the selected measurement type.

    In the area property conversion, the 1E-06 factor is used, and 1E-06 = 0.000001. For example, 1 m2 is 1000000 mm2 in Tekla Structures. In IFC, the area unit is m2, and the Tekla Structures value needs to be converted by 1E-06: 1000000 mm2 x 1E-6= 1 m2.

    In the volume property conversion, the 1E-09 factor is used, and 1E-09 = 0.000000001.

    Accuracy: Indicate the accuracy that is used when writing the property to IFC. Enter decimals, for example, 0.1 or 0.01. For example with length, when accuracy is 0.1, with a 1000 mm IFC file the value would be 1000.0. If accuracy was 0.01, the value would be 1000.00. If the accuracy was 0.5, the Tekla Structures value 1000.6 would be 1000.5, 1000.8 would be 1001.0, and 1000.2 would be 1000.0.

    You cannot change the Source value, it is either Template or UDA depending on the property that you selected.

  6. Select the desired values and click Add.
  7. To save the changes in the property set configuration file, click Save.
When you have several properties in the list, you can drag those up or down in the list. To modify the created property set, select the property set and click Modify selected property set.

Add a buildingSMART property set

You can add buildingSMART property sets to property set configuration files.

  1. In the Property set definitions dialog box, open the property set configuration file where you want to add buildingSMART property sets.
  2. Click the Import buildingSMART property sets button on the right.
  3. Select the property sets that you want to add. To do this, select the Import check box next to the property set.
    You can search for property sets using the Search box. You can also limit the number of the displayed property sets by selecting the desired property set categories, IFC entities, or IFC versions.
  4. Click Import.
    The selected buildingSMART property sets are added in the property set list. The buildingSMART property sets are protected, and you cannot edit those, but you can exclude the unnecessary buildingSMART property sets from the export, and change and edit the mapped Tekla properties.
  5. To save the changes in property set configuration file, click Save.

Delete a property set

If a property set is no longer needed, you can delete it from the configuration file.
  1. In the Property set definitions dialog box, a custom property set configuration file.
  2. Select a property set from the property set list.
  3. Click the Delete selected property sets.
  4. To save the changes in property set configuration file, click Save.
If you do not want to include the property set in the export but still want to leave the property set in the configuration, clear the Include check box next to the property set.

Delete properties from a property set

If a property is no longer needed in a property set, you can delete it.

The buildingSMART property sets (beginning with prefixes Pset_ or Qto_) are protected, and you cannot delete properties from those. However, you can exclude properties included in buildingSMART property sets, see section "Include or exclude property sets or properties" above.

  1. Open a property set configuration file in the Property set definitions dialog box.
  2. In the property set list, select a property set from which you want to delete a property.
  3. Select a property from the property list.
  4. Click the Delete selected property.
If you do not want to include the property in the export but still want to leave the property in the property set, clear the Include check box next to the property.

Duplicate a property set

When you want have a new property set that is very similar to an existing property set, you can duplicate the existing property set. You can then modify the property set so that the properties are the same but the filtering criteria is different, for example.

You cannot duplicate a buildingSMART property set.

  1. Open a property set configuration file in the Property set definitions dialog box.
  2. In the property set list, select a property set that you want to duplicate.
  3. Click Duplicate selected property set.

    The property set is duplicated and added under the original property set in the list.

  4. To modify the property set, select the duplicated property set and click Modify selected property set.
    Change the property set name, select the desired entities, and specify another selection filter, for example.

    Change the property set name, select the desired entities, or specify a selection filter that exports the property set for some other objects, for example.

  5. When you are done, click Modify.

Include or exclude property sets or properties

You can keep a property set or a property in the configuration file, but exclude it from the export.

You can also exclude buildingSMART property sets and properties.

  1. On the File menu, click Export > IFC or Export > IFC4.
  2. Select an existing property set from the Property sets list and click the Edit button.
  3. Do one of the following:
    • To export all property sets in the list, select the Include check box on the title row of the property set section.
    • To export all properties for the selected property set, select the Include check box on the title row of the properties section.
    • To export only the needed property sets, select the check boxes next to the property sets.

    • To export only the needed properties for the selected property set, select the check boxes next to the properties.

  4. To save the changes in property set configuration file, click Save.

Property set configuration file contents

A property set configuration file contains the structure of the property sets, and the data definitions for the properties inside the property sets.

When configuring property sets for IFC export in XML format, two files are needed:

  • IfcPropertySetConfigurations.xsd is a schema file that describes the structure of the XML file and is used for validation of the XML file. This file is read when the software is started. There is only one schema file in your environment. You do not need to touch this file.

  • The XML file <configuration_file_name>.xml is the actual property set configuration file.

The modified configuration files are saved in the \AdditionalPSets folder under the model, and they are also read from the system, project, and firm folders.

  • The property set XML configuration file contains the following definitions:
    • Template attribute or UDA name. Template attributes are read from contentattributes_global.lst and the user-defined attributes from the environment database.
    • Data type, such as String, Integer, Float, Timestamp, Boolean, Logical, or planeanglemeasure.
    • Unit type, such as length, area, volume, or mass.
    • Unit value scaling of unitless UDA values. Conversion factor is added so that unitless values can be converted to correspond to the global units used in the IFC files. Area and volume units need these factors.
    • Possibility to use default values.
    • Possibility to ignore the set to export if template attribute or UDA does not have a value.
  • Below is an example of the contents of a property set configuration XML file.
        <PropertySet referenceId="assemblies" isIgnored="false">
      <Name>Tekla Assembly</Name>
      <Description>Assembly Properties</Description>
      <Properties>
        <Property xsi:type="PropertySingleValueType" optional="true" isIgnored="false">
          <Name>Assembly/Cast unit Mark</Name>
          <PropertyValue xsi:type="StringValueType" stringType="IfcLabel">
            <GetValue xsi:type="TemplateVariableType">
              <TemplateName>ASSEMBLY_POS</TemplateName>
            </GetValue>
          </PropertyValue>
        </Property>
        <Property xsi:type="PropertySingleValueType" optional="true" isIgnored="false">
          <Name>Assembly/Cast unit position code</Name>
          <PropertyValue xsi:type="StringValueType" stringType="IfcLabel">
            <GetValue xsi:type="TemplateVariableType">
              <TemplateName>ASSEMBLY_POSITION_CODE</TemplateName>
            </GetValue>
          </PropertyValue>
        </Property>
        <Property xsi:type="PropertySingleValueType" optional="true" isIgnored="false">
          <Name>Assembly/Cast unit top elevation</Name>
          <PropertyValue xsi:type="StringValueType" stringType="IfcLabel">
            <GetValue xsi:type="TemplateVariableType">
              <TemplateName>ASSEMBLY_TOP_LEVEL</TemplateName>
            </GetValue>
          </PropertyValue>
        </Property>
        <Property xsi:type="PropertySingleValueType" optional="true" isIgnored="false">
          <Name>Assembly/Cast unit bottom elevation</Name>
          <PropertyValue xsi:type="StringValueType" stringType="IfcLabel">
            <GetValue xsi:type="TemplateVariableType">
              <TemplateName>ASSEMBLY_BOTTOM_LEVEL</TemplateName>
            </GetValue>
          </PropertyValue>
        </Property>
  • The configuration file also contains the rules for binding the property sets to IFC entities:
    • Binding to IFC entity type hierarchy including support for not only building elements but also for bolts, reinforcing bars, and assemblies.
    • You have the possibility to use limiting rules, such as Equal, NotEqual, LessThan, GreaterThan, LessThanOrEqual, and GreaterThanOrEqual for numbers, and Equal and NotEqual for texts.

      If you want to add any limiting rules, you need to modify your custom property set configuration file using a suitable text editor.

    • There can be any number of binding rules for any property set, but only one property set definition for each referenceId.
    • You can bind different property sets to different IFC entity types. For example, a plate may have a different property set than a beam. 
    <PropertySetBind referenceId="assemblies">
      <Rules>
        <Include entityType="IfcElementAssembly" subtypes="true" />
      </Rules>
    </PropertySetBind>
  • If no value is found for a property in the export, the export does not write the property set at all. To avoid this, add optional=true for that property in the property set.
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