#### 6.1.3.3 IfcMember

| Stab / Stabträger
| Membre

An IfcMember is a structural member designed to carry loads between or beyond points of support. It is not required to be load bearing. The orientation of the member (being horizontal, vertical or sloped) is not relevant to its definition (in contrary to IfcBeam and IfcColumn). An IfcMember represents a linear structural element from an architectural or structural modeling point of view and shall be used if it cannot be expressed more specifically as either an IfcBeam or an IfcColumn.

> NOTE The representation of a member in a structural analysis model is provided by IfcStructuralCurveMember being part of an IfcStructuralAnalysisModel.

The IFC specification provides two entities for member occurrences:

- IfcMemberStandardCase used for all occurrences of members, that have a profile defined that is swept along a directrix. The profile might be changed uniformly by a taper definition along the directrix. The profile parameter and its cardinal point of insertion can be fully described by the IfcMaterialProfileSetUsage. These beams are always represented geometricly by an 'Axis' and a 'SweptSolid' or 'AdvancedSweptSolid' shape representation (or by a 'Clipping' geometry based on the swept solid), if a 3D geometric representation is assigned. In addition they have to have a corresponding IfcMaterialProfileSetUsage assigned.

  > NOTE View definitions and implementer agreements may further constrain the applicable geometry types, such as by excluding tapering from an IfcMemberStandardCase implementation.

- IfcMember used for all other occurrences of members, particularly for members with changing profile sizes along the extrusion, or members defined by non-linear extrusion, or members having only 'Brep', or 'SurfaceModel' geometry.

> HISTORY New entity in IFC2x2 Addendum 1.

## Plumbing System Design

Instance diagram

Identity

The Identity concept applies to this entity.

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Export |  |  |  |  |  |  |  | R |  |  | R | R | R

Object Typing

The Object Typing concept applies to this entity as shown in Table 29.

Type
IfcMemberType
Table 29 — IfcMember Object Typing

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Export |  |  |  |  |  |  |  |  |  |  | R |  | R

Properties for Occurrences

The Properties for Occurrences concept applies to this entity as shown in Table 30.

PredefinedType | Name
--- | ---
| Pset_MemberCommon
Table 30 — IfcMember Properties for Occurrences

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--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Import |  |  |  |  |  |  |  |  |  |  |  |  |
Export |  |  |  |  |  |  |  |  |  |  | O |  | O

Material Profile Set

The Material Profile Set concept applies to this entity.

The material of the IfcMember is defined by the IfcMaterialProfileSet or as fallback by IfcMaterial, and it is attached either directly or at the IfcMemberType.

> NOTE It is illegal to assign an IfcMaterialProfileSetUsage to an IfcMember. Only the subtype IfcMemberStandardCase supports this concept.

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Export |  |  |  |  |  |  |  |  |  |  | R |  | R

Placement

The Placement concept applies to this entity.

The local placement for IfcMember 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.

- The PlacementRelTo relationship of IfcLocalPlacement shall point (if given) to the local placement of the same IfcSpatialStructureElement, which is used in the ContainedInStructure inverse attribute, or to a spatial structure element at a higher level, referenced by that.
- If the relative placement is not used, the absolute placement is defined within the world coordinate system.

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Export |  |  |  |  |  |  |  |  |  |  | R |  | R

Axis Geometry

The Axis Geometry concept applies to this entity as shown in Table 31.

RepresentationType | Geometry
--- | ---
Curve3D | IfcBoundedCurve
Table 31 — IfcMember Axis Geometry

The axis representation can be used to represent the system length of a member that may extent the body length of the member.

Exchange |  |  |  |  |  |  |  |  |  |  |  |  |
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Import |  |  |  |  |  |  |  |  |  |  |  |  |
Export |  |  |  |  |  |  |  |  |  |  | R |  | R

Body Geometry

The Body Geometry concept applies to this entity as shown in Table 32.

RepresentationType | Geometry
--- | ---
SweptSolid | IfcExtrudedAreaSolid
Clipping | IfcBooleanClippingResult
AdvancedSweptSolid | IfcSweptAreaSolid
SurfaceModel | IfcFaceBasedSurfaceModel
Brep | IfcFacetedBrep
MappedRepresentation | IfcMappedItem
Table 32 — IfcMember Body Geometry

The body representation of IfcBeam can be represented using the representation types 'SweptSolid', 'Clipping', 'AdvancedSweptSolid', 'MappedRepresentation', 'SurfaceModel', and 'Brep'. The representation types 'SurfaceModel' and 'Brep' are explained at IfcBuildingElement.

SweptSolid Representation Type

The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

- RepresentationIdentifier : 'Body'
- RepresentationType : 'SweptSolid'

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

- Solid: IfcExtrudedAreaSolid, IfcRevolvedAreaSolid shall be supported
- Profile: all subtypes of IfcProfileDef (with exception of IfcArbitraryOpenProfileDef)
- Extrusion: All extrusion directions shall be supported.

Figure 103 illustrates a 'SweptSolid' geometric representation. There are no restrictions or conventions on how to use the local placement (black), solid of extrusion placement (red) and profile placement (green).

Figure 103 — Member swept solid

Clipping Representation Type

The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

- RepresentationIdentifier : 'Body'
- RepresentationType : 'Clipping'

The following constraints apply to the advanced representation:

- Solid: see 'SweptSolid' geometric representation
- Profile: see 'SweptSolid' geometric representation
- Extrusion: see 'SweptSolid' geometric representation
- Boolean result: The IfcBooleanClippingResult shall be supported, allowing for Boolean differences between the swept solid (here IfcExtrudedAreaSolid) and one or several IfcHalfSpaceSolid (or its subtypes).

Figure 104 illustrates a 'Clipping' geometric representation with use of IfcBooleanClippingResult between an IfcExtrudedAreaSolid and an IfcHalfSpaceSolid to create a clipped body.

Figure 104 — Member clipping

AdvancedSweptSolid Representation Type

The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

- RepresentationIdentifier : 'Body'
- RepresentationType : 'AdvancedSweptSolid'

The following additional constraints apply to the 'AdvancedSweptSolid' representation type:

- Solid: IfcSurfaceCurveSweptAreaSolid, IfcFixedReferenceSweptAreaSolid, IfcExtrudedAreaSolidTapered, IfcRevolvedAreaSolidTapered shall be supported.

  > NOTE View definitions and implementer agreements can further constrain the allowed swept solid types.

- Profile: see 'SweptSolid' geometric representation
- Extrusion: not applicable

MappedRepresentation Representation Type

The 'MappedRepresentation' representation type is 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:

- RepresentationIdentifier : 'Body'
- RepresentationType : 'MappedRepresentation'

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

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Import |  |  |  |  |  |  |  |  |  |  |  |  |
Export |  |  |  |  |  |  |  |  |  |  | R |  | R

XSD Specification:

<xs:element name="IfcMember" type="ifc:IfcMember" substitutionGroup="ifc:IfcBuildingElement" nillable="true"/>
<xs:complexType name="IfcMember">
<xs:complexContent>
<xs:extension base="ifc:IfcBuildingElement"/>
</xs:complexContent>
</xs:complexType>

EXPRESS Specification:

ENTITY IfcMember

| SUBTYPE OF (IfcBuildingElement);

PredefinedType | : | OPTIONAL IfcStrippedOptional;

| WHERE

CorrectPredefinedType | : | NOT(EXISTS(PredefinedType)) OR (PredefinedType <> IfcMemberTypeEnum.USERDEFINED) OR ((PredefinedType = IfcMemberTypeEnum.USERDEFINED) AND EXISTS (SELF\IfcObject.ObjectType));
CorrectTypeAssigned | : | (SIZEOF(IsTypedBy) = 0) OR ('IFCSHAREDBLDGELEMENTS.IFCMEMBERTYPE' IN TYPEOF(SELF\IfcObject.IsTypedBy[1].RelatingType));

END_ENTITY;

Attribute Definitions:

PredefinedType | : | Predefined generic type for a member that is specified in an enumeration. There may be a property set given for the predefined types. NOTE The PredefinedType shall only be used, if no IfcMemberType is assigned, providing its own IfcMemberType.PredefinedType. IFC4 CHANGE The attribute has been added at the end of the entity definition.

Formal Propositions:

CorrectPredefinedType | : | Either the PredefinedType attribute is unset (e.g. because an IfcMemberType is associated), or the inherited attribute ObjectType shall be provided, if the PredefinedType is set to USERDEFINED.
CorrectTypeAssigned | : | Either there is no member type object associated, i.e. the IsTypedBy inverse relationship is not provided, or the associated type object has to be of type IfcMemberType.

Inheritance Graph:

ENTITY IfcMember

| 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 IfcObject

ObjectType | : | OPTIONAL IfcStrippedOptional;

| INVERSE

IsDeclaredBy | : | SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects;
Declares | : | SET OF IfcRelDefinesByObject FOR RelatingObject;
IsTypedBy | : | SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects;
IsDefinedBy | : | SET OF IfcRelDefinesByProperties FOR RelatedObjects;

| ENTITY IfcProduct

ObjectPlacement | : | OPTIONAL IfcObjectPlacement;
Representation | : | OPTIONAL IfcProductRepresentation;

| INVERSE

ReferencedBy | : | SET OF IfcRelAssignsToProduct FOR RelatingProduct;

| ENTITY IfcElement

Tag | : | OPTIONAL IfcStrippedOptional;

| INVERSE

ConnectedTo | : | SET OF IfcRelConnectsElements FOR RelatingElement;
IsInterferedByElements | : | SET OF IfcRelInterferesElements FOR RelatedElement;
InterferesElements | : | SET OF IfcRelInterferesElements FOR RelatingElement;
HasOpenings | : | SET OF IfcRelVoidsElement FOR RelatingBuildingElement;
ProvidesBoundaries | : | SET OF IfcRelSpaceBoundary FOR RelatedBuildingElement;
ConnectedFrom | : | SET OF IfcRelConnectsElements FOR RelatedElement;
ContainedInStructure | : | SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements;

| ENTITY IfcBuildingElement

| INVERSE

| ENTITY IfcMember

PredefinedType | : | OPTIONAL IfcStrippedOptional;

END_ENTITY;

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