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IfcBuildingElement

Definition from ISO 6707-1:1989: Major functional part of a building, examples are foundation, floor, roof, wall.

Definition from buildingSMART: The building element comprises all elements that are primarily part of the construction of a building, i.e., its structural and space separating system.

EXAMPLEs of building elements are walls, beams, or doors, they are all physically existent and tangible things.

The IfcBuildingElement utilizes the following capabilities mainly through inverse attributes referencing objectified relationships:

  1. Grouping - being part of a logical group of objects
  2. Work processes - reference to work tasks, in which this building element is used
  3. Aggregation - aggregated together with other elements to form an aggregate
  4. Material - assignment of material used by this building element
  5. Classification - assigned reference to an external classification
  6. Documentation - assigned reference to an external documentation
  7. Type - reference to the common product type information for the element occurrence
  8. Properties - reference to all attached properties, including quantities
  9. Connection - connectivity to other elements, including the definition of the joint
  10. Realization - information, whether the building element is used to realize a connection (e.g. as a weld in a connection between two members)
  11. Ports - information, whether the building element has ports for system connections (note: normally not used, this relationship is inherited from IfcElement and mainly applicable to IfcDistributionElement's)
  12. Assignment to spatial structure - hierarchical assignment to the right level within the spatial structure
  13. Reference to spatial structure(s) - non hierarchical reference to one or more elements within the spatial structure (e.g. a curtain wall, being contained in the building, references several stories)
  14. Boundary - provision of space boundaries by this building element
  15. Coverings - assignment of covering elements to this building element (note: normally covering elements are assigned to the space, only used for special cases)
  16. Voids - information, whether the building element includes openings, recesses or other voids
  17. Projection - information, whether the building element has projections (such as a fascia)
  18. Filling - information whether the building element is used to fill openings
  19. Structural member reference - information whether the building element is represented in a structural analysis model by a structural member

HISTORY New entity in IFC Release 1.0

Quantity Use Definition:

The quantities relating to the IfcBuildingElement are defined by the IfcElementQuantity and attached by the IfcRelDefinesByProperties. A detailed specification for individual quantities is introduced at the level of subtypes of IfcBuildingElement.

Geometry Use Definitions

The geometric representation of any IfcBuildingElement is given by the IfcProductDefinitionShape and IfcLocalPlacement allowing multiple geometric representations.

Local Placement

The local placement for any IfcBuildingElement is defined in its supertype IfcProduct. It is defined by the IfcLocalPlacement, which defines the local coordinate system that is referenced by all geometric representations. Further constraints are defined at the level of its subtypes.

Geometric Representations

Any IfcBuildingElement can be represented by one or several geometric representations. A detailed specification is introduced at the level of subtypes. Only the general representation types 'BoundingBox', 'SurfaceModel', 'Brep', and 'MappedRepresentation' are defined here.

Bounding Box Representation

Any IfcBuildingElement may be represented as a bounding box, which shows the maximum extend of the body within the coordinated system established by the IfcLocalPlacement. The bounding box representation is the simplest geometric representation available. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

bounding box

The bounding box representation is given by an IfcShapeRepresentation, which includes a single item, an IfcBoundingBox.

SurfaceModel Representation

Any IfcBuildingElement (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 models. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

In some cases it may be useful to also expose a simple representation as a bounding box representation of the same complex shape.

bounding box

The surface model representation is given by an IfcShapeRepresentation, which includes a single item, which is either:

  • IfcShellBasedSurfaceModel, or
  • IfcFaceBasedSurfaceModel.

Brep Representation

Any IfcBuildingElement (so far no further constraints are defined at the level of its subtypes) may be represented as a single or multiple Boundary Representation elements (which are restricted to faceted Brep with or without voids). The Brep representation allows for the representation of complex element shape. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

In some cases it may be useful to also expose a simple representation as a bounding box representation of the same complex shape.

Brep representation TheBrep representation is given by an IfcShapeRepresentation, which includes one or more items, all of type IfcManifoldSolidBrep.

MappedRepresentation

Any IfcBuildingElement (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 following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

The same constraints, as given for the 'SurfaceModel' and the 'Brep' geometric representation, shall apply to the MappedRepresentation of the IfcRepresentationMap.

EXPRESS specification:

ENTITY IfcBuildingElement
ABSTRACT SUPERTYPE OF (ONEOF(IfcBuildingElementProxy, IfcCovering, IfcBeam, IfcColumn, IfcCurtainWall, IfcDoor, IfcMember, IfcRailing, IfcRamp, IfcRampFlight, IfcWall, IfcSlab, IfcStairFlight, IfcWindow, IfcStair, IfcRoof, IfcPile, IfcFooting, IfcBuildingElementComponent, IfcPlate))
SUBTYPE OF ( IfcElement);
END_ENTITY;

Inheritance graph

ENTITY IfcBuildingElement;
ENTITY IfcRoot;
GlobalId  :  IfcGloballyUniqueId;
OwnerHistory  :  IfcOwnerHistory;
Name  :  OPTIONAL IfcLabel;
Description  :  OPTIONAL IfcText;
ENTITY IfcObjectDefinition;
INVERSE
HasAssignments  :  SET OF IfcRelAssigns FOR RelatedObjects;
IsDecomposedBy  :  SET OF IfcRelDecomposes FOR RelatingObject;
Decomposes  :  SET [0:1] OF IfcRelDecomposes FOR RelatedObjects;
HasAssociations  :  SET OF IfcRelAssociates FOR RelatedObjects;
ENTITY IfcObject;
ObjectType  :  OPTIONAL IfcLabel;
INVERSE
IsDefinedBy  :  SET OF IfcRelDefines FOR RelatedObjects;
ENTITY IfcProduct;
ObjectPlacement  :  OPTIONAL IfcObjectPlacement;
Representation  :  OPTIONAL IfcProductRepresentation;
INVERSE
ReferencedBy  :  SET OF IfcRelAssignsToProduct FOR RelatingProduct;
ENTITY IfcElement;
Tag  :  OPTIONAL IfcIdentifier;
INVERSE
HasStructuralMember  :  SET OF IfcRelConnectsStructuralElement FOR RelatingElement;
FillsVoids  :  SET [0:1] OF IfcRelFillsElement FOR RelatedBuildingElement;
ConnectedTo  :  SET OF IfcRelConnectsElements FOR RelatingElement;
HasCoverings  :  SET OF IfcRelCoversBldgElements FOR RelatingBuildingElement;
HasProjections  :  SET OF IfcRelProjectsElement FOR RelatingElement;
ReferencedInStructures  :  SET OF IfcRelReferencedInSpatialStructure FOR RelatedElements;
HasPorts  :  SET OF IfcRelConnectsPortToElement FOR RelatedElement;
HasOpenings  :  SET OF IfcRelVoidsElement FOR RelatingBuildingElement;
IsConnectionRealization  :  SET OF IfcRelConnectsWithRealizingElements FOR RealizingElements;
ProvidesBoundaries  :  SET OF IfcRelSpaceBoundary FOR RelatedBuildingElement;
ConnectedFrom  :  SET OF IfcRelConnectsElements FOR RelatedElement;
ContainedInStructure  :  SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements;
ENTITY IfcBuildingElement;
END_ENTITY;