IFC 4.3.x development

6.1.3.3 IfcBeamType

Change log

IFC4

additionswhere_rulesCorrectPredefinedType

IFC4X3_RC3

modificationssupertypeChanged from IfcBuildingElementType to IfcBuiltElementType

6.1.3.3.1 Semantic definitions at the entity

The element type IfcBeamType defines commonly shared information for occurrences of beams. The set of shared information may include:

  • common properties within shared property sets
  • common material information
  • common profile definitions
  • common shape representations

It is used to define a beam specification, or beam style (the specific product information that is common to all occurrences of that beam type). Beam types may be exchanged without being already assigned to occurrences.

Occurrences of the IfcBeamType within building models are represented by instances of IfcBeamStandardCase if the IfcBeamType has a single associated IfcMaterialProfileSet; otherwise they are represented by instances of IfcBeam. Occurrences of the IfcBeamType within structural analysis models are represented by instances of IfcStructuralCurveMember, or its applicable subtypes.

HISTORY  New entity in IFC2x2.

6.1.3.3.1 Attributes

# 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.
IfcTypeObject
5 ApplicableOccurrenceOPTIONAL IfcIdentifier The attribute optionally defines the data type of the occurrence object, to which the assigned type object can relate. If not present, no instruction is given to which occurrence object the type object is applicable. The following conventions are used:

* The IFC entity name of the applicable occurrence using the IFC naming convention, CamelCase with IFC prefix

* It can be optionally followed by the predefined type after the separator "/" (forward slash), using uppercase

* If one type object is applicable to many occurrence objects, then those occurrence object names should be separate by comma "," forming a comma separated string.

> EXAMPLE Refering to a furniture as applicable occurrence entity would be expressed as 'IfcFurnishingElement', refering to a brace as applicable entity would be expressed as 'IfcMember/BRACE', refering to a wall and wall standard case would be expressed as 'IfcWall, IfcWallStandardCase'.
6 HasPropertySets OPTIONAL SET [1:?] OF IfcPropertySetDefinition Set ~~list~~ of unique property sets, that are associated with the object type and are common to all object occurrences referring to this object type.

> IFC2x3 CHANGE  The attribute aggregate type has been changed from LIST to SET.
Types SET [0:1] OF IfcRelDefinesByType FOR RelatingType Reference to the relationship IfcRelDefinedByType and thus to those occurrence objects, which are defined by this type.
IfcTypeProduct
7 RepresentationMaps OPTIONAL LIST [1:?] OF UNIQUE IfcRepresentationMap List of unique representation maps. Each representation map describes a block definition of the shape of the product style. By providing more than one representation map, a multi-view block definition can be given.
8 Tag OPTIONAL IfcLabel The tag (or label) identifier at the particular type of a product, e.g. the article number (like the EAN). It is the identifier at the specific level.
ReferencedBy SET [0:?] OF IfcRelAssignsToProduct FOR RelatingProductReference to the IfcRelAssignsToProduct relationship, by which other products, processes, controls, resources or actors (as subtypes of IfcObjectDefinition) can be related to this product type.

> IFC4 CHANGE  New inverse relationship.
IfcElementType
9 ElementType 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.
IfcBuiltElementType
IfcBeamType
10 PredefinedType IfcBeamTypeEnum Identifies the predefined types of a beam element from which the type required may be set.

6.1.3.3.2 Entity inheritance

dot_inheritance IfcBeamType IfcBeamType IfcBuiltElementType IfcBuiltElementType IfcBeamType->IfcBuiltElementType IfcBuiltElementType_children 23 more... IfcBuiltElementType_children->IfcBuiltElementType IfcElementType IfcElementType IfcBuiltElementType->IfcElementType IfcElementType_children 7 more... IfcElementType_children->IfcElementType IfcTypeProduct IfcTypeProduct IfcElementType->IfcTypeProduct IfcTypeProduct_children 3 more... IfcTypeProduct_children->IfcTypeProduct IfcTypeObject IfcTypeObject IfcTypeProduct->IfcTypeObject IfcTypeProcess IfcTypeProcess IfcTypeProcess->IfcTypeObject IfcObjectDefinition IfcObjectDefinition IfcTypeObject->IfcObjectDefinition IfcTypeResource IfcTypeResource IfcTypeResource->IfcTypeObject IfcContext IfcContext IfcContext->IfcObjectDefinition IfcRoot IfcRoot IfcObjectDefinition->IfcRoot IfcObject IfcObject IfcObject->IfcObjectDefinition IfcPropertyDefinition IfcPropertyDefinition IfcPropertyDefinition->IfcRoot IfcRelationship IfcRelationship IfcRelationship->IfcRoot

6.1.3.3.3 Definitions applying to General Usage

6.1.3.3.3.1 Body Geometry

The IfcBeamType may define the shared geometric representation for all beam occurrences. The RepresentationMaps attribute refers to a list of IfcRepresentationMap's, that allow for multiple geometric representations (e.g. with IfcShaperepresentation's having an RepresentationIdentifier 'Box', 'Axis', or 'Body'). It is only applicable if the IfcBeamType has only occurrences of type IfcBeam (See geometric use definition of IfcBeam for further information).

NOTE  If the IfcBeamType has an associated IfcMaterialProfileSet, then no shared geometric representation shall be provided.
NOTE  The product shape representations are defined as RepresentationMaps (attribute of the supertype IfcTypeProduct), which get assigned by an element occurrence instance through the IfcShapeRepresentation.Item[n] being an IfcMappedItem. See IfcTypeProduct for further information.
NOTE  The values of attributes RepresentationIdentifier and RepresentationType of IfcShapeRepresentation are restricted in the same way as those for IfcBeam and IfcBeamStandardCase
Geometry RepresentationType
'IfcExtrudedAreaSolid''SweptSolid'
'IfcFacetedBrep' 'Brep'

6.1.3.3.3.2 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.

6.1.3.3.3.3 Identity

IfcRoot assigns the globally unique ID. In addition it may provide for a name and a description about the concept.

6.1.3.3.3.4 Material Profile Set

The material of the IfcBeamType is defined by the IfcMaterialProfileSet or as fall back by IfcMaterial and attached by the IfcRelAssociatesMaterial.RelatingMaterial. It is accessible by the inverse HasAssociations relationship.

NOTE  It is illegal to assign an IfcMaterial to an IfcBeamType, if there is at least one occurrence of IfcBeamStandardCase for this type.

The shared profile definition is defined by assigning an IfcMaterialProfileSet (see material use definition above). The IfcMaterialProfile refers to the subtype of IfcProfileDef that is the common profile for all beam occurrence, if used. It is only applicable if the IfcBeamType has only occurrences of type IfcBeamStandardCase (see definition of IfcBeamStandardCase for further information).

NOTE  The attribute ProfileName of the IfcProfileDef subtype, referenced in IfcMaterialProfile should contain a standardized profile name according to local standards. However, an additional geometric representation of the profile is necessary (such as IfcExtrudedAreaSolid). An importing application is allowed to check for the existence of the profile name: in case of identifying it as a standardized name, the corresponding profile geometry and possibly other cross sectional properties can be read from a library. Otherwise the geometric representation and possible non geometric IfcProfileProperties have to be used.

6.1.3.3.3.5 Product Type Shape

The RepresentationMaps define the type product shape and multiple geometric representations can be assigned. If a product occurrence is assigned to the type by using the IfcRelDefinesByType relationship, then these occurrences have to reference the representation maps. The reference is created by one or multiple IfcShapeRepresentation's having an IfcMappedItem as Items, that places the IfcRepresentationMap of the type product into the spatial contexts, i.e. by using an Cartesian transformation operator to transform the IfcRepresentationMap into the object coordinate system of the product occurrence.

Figure 136 illustrates an example of referencing a representation map by the shape representation of a product occurrence. Here the Cartesian transformation operator only uses translation, but no rotation, mirroring, or scaling.

representation map

Figure 136 — Product type geometry with single placement

Figure 137 illustrates an example of referencing a representation multiple times map by the shape representation of a product occurrence. Here the Cartesian transformation operator only uses translation, but no rotation, mirroring, or scaling. The different translation values determine the pattern of the multiple placement.

representation map

Figure 137 — Product type geometry with multiple placement

6.1.3.3.3.6 Revision Control

Ownership, history, and merge state is captured using IfcOwnerHistory.

6.1.3.3.4 Formal representations

ENTITY IfcBeamType
 SUBTYPE OF (IfcBuiltElementType);
	PredefinedType : IfcBeamTypeEnum;
 WHERE
	CorrectPredefinedType : (PredefinedType <> IfcBeamTypeEnum.USERDEFINED) OR
((PredefinedType = IfcBeamTypeEnum.USERDEFINED) AND EXISTS(SELF\IfcElementType.ElementType));
END_ENTITY;