IFC 4.3.x development
5.4.3.6 IfcBuiltElement
Change log
IFC4X3_RC3
| added |
5.4.3.6.1 Semantic definitions at the entity
The built element comprises all elements that are primarily part of the construction of a built facility, i.e., its structural and space separating system. Built elements are all physically existent and tangible things
NOTE Definition from ISO 6707-1:
Major functional part of a building, examples are foundation, floor, roof, wall.
This IfcBuiltElement is a generalization of all elements that participate in a building system. Typical examples of IfcBuiltElement's are (among others):
- built elements within a space separation systems
- built elements within an enclosure system (such as a facade)
- built elements within a fenestration system
- built elements within a load bearing system
- built elements within a foundation system
EXAMPLE built elements are walls, curtain wall, doors, columns, pile, and others.
The IfcBuiltElement can be instantiated in the case when arbitrary built elements cannot be expressed by a subtype of IfcBuiltElement.
HISTORY New entity in IFC1.0
Formal Propositions
MaxOneMaterialAssociation
There should be only a maximum of one material association assigned to an building element.
NOTE The material association can assign a single material, a set of materials, a set of material layers, or a set of material profiles by a single association relationship.
FC2x4 CHANGE The where rule has been promoted from the subtype IfcWall.
| # | Attribute | Type | Description |
|---|---|---|---|
| IfcRoot | |||
| 1 | GlobalId | IfcGloballyUniqueId | Assignment of a globally unique identifier within the entire software world. |
| 2 | OwnerHistory | OPTIONAL IfcOwnerHistory | Assignment of the information about the current ownership of that object, including owning actor, application, local identification and information captured about the recent changes of the object, > NOTE only the last modification in stored - either as addition, deletion or modification. > IFC4 CHANGE The attribute has been changed to be OPTIONAL. |
| 3 | Name | OPTIONAL IfcLabel | Optional name for use by the participating software systems or users. For some subtypes of IfcRoot the insertion of the Name attribute may be required. This would be enforced by a where rule. |
| 4 | Description | OPTIONAL IfcText | Optional description, provided for exchanging informative comments. |
| IfcObjectDefinition | |||
| HasAssignments | SET [0:?] OF IfcRelAssigns FOR RelatedObjects | Reference to the relationship objects, that assign (by an association relationship) other subtypes of IfcObject to this object instance. Examples are the association to products, processes, controls, resources or groups. | |
| Nests | SET [0:1] OF IfcRelNests FOR RelatedObjects | References to the decomposition relationship being a nesting. It determines that this object definition is a part within an ordered whole/part decomposition relationship. An object occurrence or type can only be part of a single decomposition (to allow hierarchical strutures only). > IFC4 CHANGE The inverse attribute datatype has been added and separated from Decomposes defined at IfcObjectDefinition. | |
| IsNestedBy | SET [0:?] OF IfcRelNests FOR RelatingObject | References to the decomposition relationship being a nesting. It determines that this object definition is the whole within an ordered whole/part decomposition relationship. An object or object type can be nested by several other objects (occurrences or types). > IFC4 CHANGE The inverse attribute datatype has been added and separated from IsDecomposedBy defined at IfcObjectDefinition. | |
| HasContext | SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions | References to the context providing context information such as project unit or representation context. It should only be asserted for the uppermost non-spatial object. > IFC4 CHANGE The inverse attribute datatype has been added. | |
| IsDecomposedBy | SET [0:?] OF IfcRelAggregates FOR RelatingObject | References to the decomposition relationship being an aggregation. It determines that this object definition is whole within an unordered whole/part decomposition relationship. An object definitions can be aggregated by several other objects (occurrences or parts). > IFC4 CHANGE The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates. | |
| Decomposes | SET [0:1] OF IfcRelAggregates FOR RelatedObjects | References to the decomposition relationship being an aggregation. It determines that this object definition is a part within an unordered whole/part decomposition relationship. An object definitions can only be part of a single decomposition (to allow hierarchical strutures only). > IFC4 CHANGE The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates. | |
| HasAssociations | SET [0:?] OF IfcRelAssociates FOR RelatedObjects | Reference to the relationship objects, that associates external references or other resource definitions to the object.. Examples are the association to library, documentation or classification. | |
| IfcObject | |||
| 5 | ObjectType | OPTIONAL IfcLabel | The type denotes a particular type that indicates the object further. The use has to be established at the level of instantiable subtypes. In particular it holds the user defined type, if the enumeration of the attribute PredefinedType is set to USERDEFINED. |
| IsDeclaredBy | SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects | Link to the relationship object pointing to the declaring object that provides the object definitions for this object occurrence. The declaring object has to be part of an object type decomposition. The associated IfcObject, or its subtypes, contains the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes. > IFC4 CHANGE New inverse relationship, change made with upward compatibility for file based exchange. | |
| Declares | SET [0:?] OF IfcRelDefinesByObject FOR RelatingObject | Link to the relationship object pointing to the reflected object(s) that receives the object definitions. The reflected object has to be part of an object occurrence decomposition. The associated IfcObject, or its subtypes, provides the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes. > IFC4 CHANGE New inverse relationship, change made with upward compatibility for file based exchange. | |
| IsTypedBy | SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects | Set of relationships to the object type that provides the type definitions for this object occurrence. The then associated IfcTypeObject, or its subtypes, contains the specific information (or type, or style), that is common to all instances of IfcObject, or its subtypes, referring to the same type. > IFC4 CHANGE New inverse relationship, the link to IfcRelDefinesByType had previously be included in the inverse relationship IfcRelDefines. Change made with upward compatibility for file based exchange. | |
| IsDefinedBy | SET [0:?] OF IfcRelDefinesByProperties FOR RelatedObjects | Set of relationships to property set definitions attached to this object. Those statically or dynamically defined properties contain alphanumeric information content that further defines the object. > IFC4 CHANGE The data type has been changed from IfcRelDefines to IfcRelDefinesByProperties with upward compatibility for file based exchange. | |
| IfcProduct | |||
| 6 | ObjectPlacement | OPTIONAL IfcObjectPlacement | Placement of the product in space, the placement can either be absolute (relative to the world coordinate system), relative (relative to the object placement of another product), or constraint (e.g. relative to grid axes). It is determined by the various subtypes of IfcObjectPlacement, which includes the axis placement information to determine the transformation for the object coordinate system. |
| 7 | Representation | IfcProductDefinitionShape | Reference to the representations of the product, being either a representation (IfcProductRepresentation) or as a special case a shape representations (IfcProductDefinitionShape). The product definition shape provides for multiple geometric representations of the shape property of the object within the same object coordinate system, defined by the object placement. |
| ReferencedBy | SET [0:?] OF IfcRelAssignsToProduct FOR RelatingProduct | Reference to the IfcRelAssignsToProduct relationship, by which other products, processes, controls, resources or actors (as subtypes of IfcObjectDefinition) can be related to this product. | |
| PositionedRelativeTo | SET [0:1] OF IfcRelPositions FOR RelatedProducts | ||
| ReferencedInStructures | SET [0:?] OF IfcRelReferencedInSpatialStructure FOR RelatedElements | ||
| IfcElement | |||
| 8 | Tag | OPTIONAL IfcIdentifier | The tag (or label) identifier at the particular instance of a product, e.g. the serial number, or the position number. It is the identifier at the occurrence level. |
| FillsVoids | SET [0:1] OF IfcRelFillsElement FOR RelatedBuildingElement | Reference to the IfcRelFillsElement Relationship that puts the element as a filling into the opening created within another element. | |
| ConnectedTo | SET [0:?] OF IfcRelConnectsElements FOR RelatingElement | Reference to the element connection relationship. The relationship then refers to the other element to which this element is connected to. | |
| IsInterferedByElements | SET [0:?] OF IfcRelInterferesElements FOR RelatedElement | Reference to the interference relationship to indicate the element that is interfered. The relationship, if provided, indicates that this element has an interference with one or many other elements. > NOTE There is no indication of precedence between IsInterferedByElements and InterferesElements. > IFC4 CHANGE New inverse relationship. | |
| InterferesElements | SET [0:?] OF IfcRelInterferesElements FOR RelatingElement | Reference to the interference relationship to indicate the element that interferes. The relationship, if provided, indicates that this element has an interference with one or many other elements. > NOTE There is no indication of precedence between IsInterferedByElements and InterferesElements. > IFC4 CHANGE New inverse relationship. | |
| HasProjections | SET [0:?] OF IfcRelProjectsElement FOR RelatingElement | Projection relationship that adds a feature (using a Boolean union) to the IfcBuildingElement. | |
| HasOpenings | SET [0:?] OF IfcRelVoidsElement FOR RelatingBuildingElement | Reference to the IfcRelVoidsElement relationship that creates an opening in an element. An element can incorporate zero-to-many openings. For each opening, that voids the element, a new relationship IfcRelVoidsElement is generated. | |
| IsConnectionRealization | SET [0:?] OF IfcRelConnectsWithRealizingElements FOR RealizingElements | Reference to the connection relationship with realizing element. The relationship, if provided, assigns this element as the realizing element to the connection, which provides the physical manifestation of the connection relationship. | |
| ProvidesBoundaries | SET [0:?] OF IfcRelSpaceBoundary FOR RelatedBuildingElement | Reference to space boundaries by virtue of the objectified relationship IfcRelSpaceBoundary. It defines the concept of an element bounding spaces. | |
| ConnectedFrom | SET [0:?] OF IfcRelConnectsElements FOR RelatedElement | Reference to the element connection relationship. The relationship then refers to the other element that is connected to this element. | |
| ContainedInStructure | SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements | Containment relationship to the spatial structure element, to which the element is primarily associated. This containment relationship has to be hierachical, i.e. an element may only be assigned directly to zero or one spatial structure. | |
| HasCoverings | SET [0:?] OF IfcRelCoversBldgElements FOR RelatingBuildingElement | Reference to IfcCovering by virtue of the objectified relationship IfcRelCoversBldgElement. It defines the concept of an element having coverings associated. | |
| HasSurfaceFeatures | INVALID | Reference to the IfcRelAdheresToElement relationship that adheres a IfcSurfaceFeature to an element. An element can incorporate zero-to-many surface features in one relationship. | |
5.4.3.6.1 Entity inheritance
5.4.3.6.2 Definitions applying to General Usage
5.4.3.6.2.1 Body AdvancedBrep Geometry
An IfcElement (so far no further constraints are defined at the level of its subtypes or by view definitions) may be represented as a single or multiple boundary representation models, which include advanced surfaces, usually refered to as NURBS surfaces. The 'AdvancedBrep' representation allows for the representation of complex free-form element shape.
NOTE View definitions or implementer agreements may restrict or disallow the use of 'AdvancedBrep' geometry.
5.4.3.6.2.2 Body Brep Geometry
Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a single or multiple Boundary Representation models (which are restricted to be faceted Brep's with or without voids). The Brep representation allows for the representation of complex element shape.
 |
EXAMPLE As shown in Figure 150, the Brep representation is given by an IfcShapeRepresentation, which includes one or more items, all of type IfcFacetedBrep. In some cases it may be useful to also expose a simple representation as a bounding box representation of the same complex shape. |
|
Figure 150 — Building element body boundary representation |
5.4.3.6.2.3 Body CSG Geometry
Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented a CSG primitive or CSG tree. The CSG representation allows for the representation of complex element shape.
NOTE View definitions or implementer agreements may restrict or disallow the use of 'CSG' geometry.
5.4.3.6.2.4 Body SurfaceModel Geometry
Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a single or multiple surface models, based on either shell or face based surface models. It may also include tessellated models.
 |
EXAMPLE As shown in Figure 149, the surface model representation is given by an IfcShapeRepresentation, which includes a single item which is either an IfcShellBasedSurfaceModel, or an IfcFaceBasedSurfaceModel. In some cases it may also be useful to expose a simple representation as a bounding box representation of the same complex shape. |
|
Figure 149 — Element surface model representation |
5.4.3.6.2.5 Body SurfaceOrSolidModel Geometry
Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a mixed representation, including surface and solid models.
5.4.3.6.2.6 Body Tessellation Geometry
Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a single or multiple tessellated surface models, in particular triangulated surface models.
5.4.3.6.2.7 Box Geometry
 |
EXAMPLE Any IfcElement may be represented by a bounding box, which shows the maximum extend of the body within the object coordinate system established by the IfcObjectPlacement. As shown in Figure 148, the bounding box representation is given by an IfcShapeRepresentation that includes a single item, an IfcBoundingBox. |
Figure 148 — Building element box representation |
5.4.3.6.2.8 Classification Association
Any object occurrence or object type can have a reference to a specific classification reference, i.e. to a particular facet within a classification system.
5.4.3.6.2.9 CoG Geometry
The 'CoG', Center of Gravity, shape representation is used as a means to verify the correct import by comparing the CoG of the imported geometry with the explicily provided CoG created during export.
5.4.3.6.2.10 Element Projecting
5.4.3.6.2.11 Element Voiding
5.4.3.6.2.12 FootPrint Geometry
| Type | Identifier |
|---|---|
| 'GeometricCurveSet' | 'FootPrint' |
| 'Annotation2D' | 'FootPrint' |
5.4.3.6.2.13 Identity
IfcRoot assigns the globally unique ID. In addition it may provide for a name and a description about the concept.
5.4.3.6.2.14 Mapped Geometry
Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented using the 'MappedRepresentation'. This shall be supported as it allows for reusing the geometry definition of a type at all occurrences of the same type. The results are more compact data sets.
The same constraints, as given for 'SurfaceOrSolidModel', 'SurfaceModel', 'Tessellation', 'Brep', and 'AdvancedBrep' geometric representation, shall apply to the IfcRepresentationMap.
5.4.3.6.2.15 Object Predefined Type
5.4.3.6.2.16 Object Typing
Any object occurrence can be typed by being assigned to a common object type utilizing this concept. A particular rule, restricting the applicable subtypes of IfcTypeObject that can be assigned, is introduced by overriding this concept at the level of subtypes of IfcObject.
5.4.3.6.2.17 Object User Identity
An attribute Name and optionally Description can be used for all subypes of IfcObject. For those subtypes, that have an object type definition, such as ifcBeam - IfcBeamType, the common Name and optionally Description is associated with the object type.
5.4.3.6.2.18 Product Geometric Representation
The geometric representation of any IfcProduct is provided by the IfcProductDefinitionShape allowing multiple geometric representations. It uses the Product Placement concept utilizing IfcLocalPlacement to establish an object coordinate system, within all geometric representations are founded.
NOTE A detailed specification of how to apply the local placement and which shape representaions are applicable is provided at the level of subtypes of IfcProduct and is further determined by the model view definition and implementer agreements.
5.4.3.6.2.19 Product Local Placement
The object placement for any subtype of IfcElement is defined by the IfcObjectPlacement, either IfcLocalPlacement or IfcGridPlacement, which defines the local object coordinate system that is referenced by all geometric representations of that IfcElement.
| HasPlacement |
|---|
| 'IfcLocalPlacement' |
| 'IfcLocalPlacement' |
5.4.3.6.2.20 Product Placement
The Product Placement establishes the object coordinate system and is required, if a geometric shape representation is provided for this product.
5.4.3.6.2.21 Property Sets for Objects
| PsetName |
|---|
| 'Pset_EnvironmentalImpactIndicators' |
| 'Pset_EnvironmentalImpactValues' |
| 'Pset_Condition' |
| 'Pset_ManufacturerOccurrence' |
| 'Pset_ManufacturerTypeInformation' |
| 'Pset_ServiceLife' |
| 'Pset_Warranty' |
5.4.3.6.2.22 Property Sets with Override
Any object occurrence can hold property sets, either directly at the object occurrence as element specific property sets, or at the object type, as type property sets. In this case, the properties that are provided to the object occurrence are the combinations of element specific and type properties. In case, that the same property (within the same property set, is defined both, in occurrence and type properties, the property value of the occurrence property overrides the property value of the type property.
5.4.3.6.2.23 Revision Control
Ownership, history, and merge state is captured using IfcOwnerHistory.
5.4.3.6.3 Formal representations
ENTITY IfcBuiltElement SUPERTYPE OF (ONEOF (IfcBeam ,IfcBearing ,IfcBuildingElementProxy ,IfcChimney ,IfcColumn ,IfcCourse ,IfcCovering ,IfcCurtainWall ,IfcDeepFoundation ,IfcDoor ,IfcEarthworksElement ,IfcFooting ,IfcKerb ,IfcMember ,IfcMooringDevice ,IfcNavigationElement ,IfcPavement ,IfcPlate ,IfcRail ,IfcRailing ,IfcRamp ,IfcRampFlight ,IfcRoof ,IfcShadingDevice ,IfcSlab ,IfcStair ,IfcStairFlight ,IfcTrackElement ,IfcWall ,IfcWindow)) SUBTYPE OF (IfcElement); WHERE MaxOneMaterialAssociation : SIZEOF (QUERY(temp <* SELF\IfcObjectDefinition.HasAssociations | 'IFC4X3_RC3.IFCRELASSOCIATESMATERIAL' IN TYPEOF(temp) )) <= 1; END_ENTITY;