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 buildingSMART: 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 longitudial structural member, not constrained to be predominately horizontal nor vertical, or where this semantic information is irrelevant, the entity IfcMember exists.
A particular usage type for the IfcBeam can be given (if type information is available) by refering to the type object IfcBeamType, using the IfcRelDefinesByType relationship, or (if only occurrence information is given) by using the ObjectType attribute. Recommended values are 'beam' (the default), 'joist', 'lintel', 't-beam'.
HISTORY New entity in IFC Release 1.0
Type Use Definition
IfcBeam defines the occuurence 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 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.
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:
|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 Definition
The geometric representation of IfcBeam is given by the IfcProductDefinitionShape, allowing multiple geometric representations. Included are:
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.
Currently, the use of 'SweptSolid', 'Clipping', 'Brep' and 'MappedRepresentation' representations is supported. In addition the general representation types 'SurfaceModel' and 'BoundingBox' are allowed. The geometry use definition for 'BoundingBox', 'SurfaceModel' and 'Brep' is explained at IfcBuildingElement.
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.
The following interpretation of dimension parameter applies for circular beams:
Advanced SweptSolid and Clipping Representation
The advanced geometric representation of IfcBeam is defined using the 'SweptSolid' (enhanced by additional profile types) or '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
Use of non-perpendicular extrusion to create the IfcExtrudedAreaSolid.
Use of IfcBooleanClippingResult between an IfcExtrudedAreaSolid and an IfcHalfSpaceSolid to create a clipped body.
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 standard SweptSolid and the advanced SweptSolid and Clipping geometric representation, shall apply to the MappedRepresentation of the IfcRepresentationMap.