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
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
- 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.
Common Use Definitions
The following concepts are inherited at supertypes:
- IfcRoot: Identity, Revision Control
- IfcElement: Product Placement, Box Geometry, FootPrint Geometry, Body SurfaceOrSolidModel Geometry, Body SurfaceModel Geometry, Body Tessellation Geometry, Body Brep Geometry, Body AdvancedBrep Geometry, Body CSG Geometry, Mapped Geometry
- IfcBuildingElement: Surface 3D Geometry
The Object Typing concept applies to this entity as shown in Table 126.
Table 126 — IfcMember Object Typing
Property Sets for Objects
The Property Sets for Objects concept applies to this entity as shown in Table 127.
Table 127 — IfcMember Property Sets for Objects
The Quantity Sets concept applies to this entity as shown in Table 128.
Table 128 — IfcMember Quantity Sets
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
The Spatial Containment concept applies to this entity as shown in Table 129.
|IfcBuildingStorey||Default spatial container|
|IfcBuilding||Spatial container for the element if it cannot be assigned to a building storey|
|IfcSite||Spatial container for the element in case that it is placed on site (outside of building)|
Table 129 — IfcMember Spatial Containment
The IfcMember, as any subtype of IfcBuildingElement,
may participate alternatively in one of the two different containment relationships:
- the Spatial Containment (defined here), or
- the Element Composition.
Axis 3D Geometry
The Axis 3D Geometry concept applies to this entity as shown in Table 130.
|Axis||Curve3D||IfcBoundedCurve||Three-dimensional reference curve for the member.|
Table 130 — IfcMember Axis 3D Geometry
The axis representation can be used to represent the system
length of a member that may extent the body length of the
NOTE The 'Axis' is not used to locate the
material profile set, only the subtype IfcMemberStandardCase
provides this capability.
Body SweptSolid Geometry
The Body SweptSolid Geometry concept applies to this entity.
The following additional constraints apply to the 'SweptSolid'
Figure 188 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 188 — Member swept solid
Body AdvancedSweptSolid Geometry
The Body AdvancedSweptSolid Geometry concept applies to this entity.
The following additional constraints apply to the
'AdvancedSweptSolid' representation type:
MappedRepresentation Representation Type
Body Clipping Geometry
The Body Clipping Geometry concept applies to this entity.
The following constraints apply to the 'Clipping'
- Solid: see 'SweptSolid' geometric representation
- Profile: see 'SweptSolid' geometric
- Extrusion: see 'SweptSolid' geometric
- 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 189 illustrates a 'Clipping' geometric representation with use of IfcBooleanClippingResult between an IfcExtrudedAreaSolid and an IfcHalfSpaceSolid to create a clipped body.
Figure 189 — Member clipping
The Product Assignment concept applies to this entity as shown in Table 131.
Table 131 — IfcMember Product Assignment
XSD Specification: <xs:element name="IfcMember" type="ifc:IfcMember" substitutionGroup="ifc:IfcBuildingElement" nillable="true"/>
<xs:attribute name="PredefinedType" type="ifc:IfcMemberTypeEnum" use="optional"/>
|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.RelatingType));|
|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.
|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.
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