6.1.3.21 IfcMemberType

Stab / Stabträger - Typ
Type de membre

The element type IfcMemberType defines commonly shared information for occurrences of members. Members are predominately linear building elements, often forming part of a structural system. The orientation of the member (being horizontal, vertical or sloped) is not relevant to its definition (in contrary to beam and column). The set of shared information may include:

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

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

HISTORY  New entity in IFC2x2 Addendum 1.

Common Use Definitions

The following concepts are inherited at supertypes:

 Instance diagram

Material Profile Set

The Material Profile Set concept applies to this entity.

The material of the IfcMemberType 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 IfcMemberType, if there is at least one occurrences of IfcMemberStandardCase 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 member occurrence, if used. It is only applicable if the IfcMemberType has only occurrences of type IfcMemberStandardCase (see definition of IfcMemberStandardCase 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 (e.g. 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.


Type Body Geometry

The Type Body Geometry concept applies to this entity.

The IfcMemberType may define the shared geometric representation for all member 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 IfcMemberType has only occurrences of type IfcMember (See geometric use definition of IfcMember for further information).

NOTE  If the IfcMemberType 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 IfcMember and IfcMemberStandardCase



XSD Specification:

 <xs:element name="IfcMemberType" type="ifc:IfcMemberType" substitutionGroup="ifc:IfcBuildingElementType" nillable="true"/>
 <xs:complexType name="IfcMemberType">
  <xs:complexContent>
   <xs:extension base="ifc:IfcBuildingElementType">
    <xs:attribute name="PredefinedType" type="ifc:IfcMemberTypeEnum" use="optional"/>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>

EXPRESS Specification:

ENTITY IfcMemberType
SUBTYPE OF IfcBuildingElementType;
PredefinedType : IfcMemberTypeEnum;
WHERE
CorrectPredefinedType : (PredefinedType <> IfcMemberTypeEnum.USERDEFINED) OR ((PredefinedType = IfcMemberTypeEnum.USERDEFINED) AND EXISTS(SELF\IfcElementType.ElementType));
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

Attribute Definitions:

PredefinedType : Identifies the predefined types of a linear structural member element from which the type required may be set.

Formal Propositions:

CorrectPredefinedType : The inherited attribute ElementType shall be provided, if the PredefinedType is set to USERDEFINED.

Inheritance Graph:

ENTITY IfcMemberType
ENTITY IfcRoot
GlobalId : IfcGloballyUniqueId;
OwnerHistory : OPTIONAL IfcOwnerHistory;
Name : OPTIONAL IfcLabel;
Description : OPTIONAL IfcText;
ENTITY IfcObjectDefinition
INVERSE
HasAssignments : SET OF IfcRelAssigns FOR RelatedObjects;
Nests : SET [0:1] OF IfcRelNests FOR RelatedObjects;
IsNestedBy : SET OF IfcRelNests FOR RelatingObject;
HasContext : SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions;
IsDecomposedBy : SET OF IfcRelAggregates FOR RelatingObject;
Decomposes : SET [0:1] OF IfcRelAggregates FOR RelatedObjects;
HasAssociations : SET OF IfcRelAssociates FOR RelatedObjects;
ENTITY IfcTypeObject
ApplicableOccurrence : OPTIONAL IfcIdentifier;
HasPropertySets : OPTIONAL SET [1:?] OF IfcPropertySetDefinition;
INVERSE
Types : SET [0:1] OF IfcRelDefinesByType FOR RelatingType;
ENTITY IfcTypeProduct
RepresentationMaps : OPTIONAL LIST [1:?] OF UNIQUE IfcRepresentationMap;
Tag : OPTIONAL IfcLabel;
INVERSE
ReferencedBy : SET OF IfcRelAssignsToProduct FOR RelatingProduct;
ENTITY IfcElementType
ElementType : OPTIONAL IfcLabel;
ENTITY IfcBuildingElementType
ENTITY IfcMemberType
PredefinedType : IfcMemberTypeEnum;
END_ENTITY;

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