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IfcBeam

Definition from ISO 6707-1:1989: Structural member designed to carry loads between or beyond points of support, usually narrow in relation to its length and horizontal or nearly so.

Definition from IAI: An IfcBeam is a horizontal, or nearly horizontal, structural member. It represents such a member from an architectural point of view. It is not required to be load bearing.

NOTE  For any longitudinal structural member, not constrained to be predominately horizontal nor vertical, or where this semantic information is irrelevant, the entity IfcMember exists.

HISTORY New entity in IFC Release 1.0

Type Use Definition

IfcBeam defines the occurrence of any beam, common information about beam types (or styles) is handled by IfcBeamType. The IfcBeamType (if present) may establish the common type name, usage (or predefined) type, common material layer set, common set of properties and common shape representations (using IfcRepresentationMap). The IfcBeamType is attached using the IfcRelDefinedByType.RelatingType objectified relationship and is accessible by the inverse IsDefinedBy attribute.

If no IfcBeamType is attached (i.e. if only occurrence information is given) the predefined type may be given by using the ObjectType attribute. Recommended values are 'beam' (the default), 'brace', 'joist', 'rafter', 'stringer'.

Property Set Use Definition:

The property sets relating to the IfcBeam are defined by the IfcPropertySet and attached by the IfcRelDefinesByProperties relationship. It is accessible by the inverse IsDefinedBy relationship. The following property set definitions specific to the IfcBeam are part of this IFC release:

Material Use Definition

The material of the IfcBeam is defined by the IfcMaterial or IfcMaterialList and attached by the IfcRelAssociatesMaterial.RelatingMaterial. It is accessible by the inverse HasAssociations relationship. Material information can also be given at the IfcBeamType, defining the common attribute data for all occurrences of the same type. It is then accessible by the inverse IsDefinedBy relationship pointing toIfcBeamType.HasAssociations and via IfcRelAssociatesMaterial.RelatingMaterial to IfcMaterial or IfcMaterialList. If both are given, then the material directly assigned to IfcBeam overrides the material assigned to IfcBeamType.

Quantity Use Definition:

The quantities relating to the IfcBeam are defined by the IfcElementQuantity and attached by the IfcRelDefinesByProperties relationship. It is accessible by the inverse IsDefinedBy relationship. The following quantities are foreseen, but will be subjected to the local standard of measurement used:

Name Description Value Type
NominalLength Total nominal length of the beam, not taking into account any cut-out's or other processing features. IfcQuantityLength
CrossSectionArea Total area of the cross section (or profile) of the beam. The exact definition and calculation rules depend on the method of measurement used. IfcQuantityArea
OuterSurfaceArea Total area of the extruded surfaces of the beam (not taking into account the end cap areas), normally generated as perimeter * length. IfcQuantityArea
TotalSurfaceArea Total area of the beam, normally generated as perimeter * length + 2 * cross section area. IfcQuantityArea
GrossVolume Total gross volume of the beam, not taking into account possible processing features (cut-out's, etc.) or openings and recesses. The exact definition and calculation rules depend on the method of measurement used. IfcQuantityVolume
NetVolume Total net volume of the beam, taking into account possible processing features (cut-out's, etc.) or openings and recesses. The exact definition and calculation rules depend on the method of measurement used. IfcQuantityVolume
GrossWeight Total gross weight of the beam without add-on parts, not taking into account possible processing features (cut-out's, etc.) or openings and recesses. IfcQuantityWeight
NetWeight Total net weight of the beam without add-on parts, taking into account possible processing features (cut-out's, etc.) or openings and recesses. IfcQuantityWeight

Containment Use Definition

The IfcBeam, as any subtype of IfcBuildingElement, may participate in two different containment relationships. The first (and in most implementation scenarios mandatory) relationship is the hierachical spatial containment, the second (optional) relationship is the aggregation within an element assembly.

Geometry Use Definitions:

The geometric representation of IfcBeam is given by the IfcProductDefinitionShape, allowing multiple geometric representations. Included are:

Local Placement

The local placement for IfcBeam 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.

Geometric Representations

Currently, the use of 'SweptSolid', 'Clipping' and 'MappedRepresentation' representations is supported. In addition the general representation types 'SurfaceModel', 'Brep', and 'BoundingBox' are allowed. The geometry use definition for 'BoundingBox', 'SurfaceModel' and 'Brep' is explained at IfcBuildingElement.

SweptSolid Representation

The standard geometric representation of IfcBeam is defined using the 'SweptSolid' representation. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

The following additional constraints apply to the 'SweptSolid' representation:

EXAMPLE: standard geometric representation.
standard beam

The following interpretation of dimension parameter applies for rectangular beams:

  • IfcRectangleProfileDef.YDim interpreted as beam width
  • IfcRectangleProfileDef.XDim interpreted as beam depth
The following interpretation of dimension parameter applies for circular beams:
  • IfcCircleProfileDef.Radius interpreted as beam radius.
non-perpendicular extrusion

Use of non-perpendicular extrusion to create the IfcExtrudedAreaSolid.

Clipping Representation

The advanced geometric representation of IfcBeam is defined using the 'Clipping' geometry. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

The following constraints apply to the advanced representation:

EXAMPLE advanced geometric representation
clipped beam
Use of IfcBooleanClippingResult between an IfcExtrudedAreaSolid and an IfcHalfSpaceSolid to create a clipped body.

MappedRepresentation

In addition to the standard and advanced geometric representation of IfcBeam that is defined using the SweptSolid or Clipping geometry, also the MappedRepresentation, shall be supported as it allows for reusing the geometry definition of the beam 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 'SweptSolid' and 'Clipping' geometric representation, shall apply to the MappedRepresentation of the IfcRepresentationMap.


EXPRESS specification:

ENTITY IfcBeam
SUBTYPE OF ( IfcBuildingElement);
END_ENTITY;

Inheritance graph

ENTITY IfcBeam;
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;
ENTITY IfcBeam;
END_ENTITY;