IfcMember

Semantic definitions at the entity

Entity definition

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 location of the member (being horizontal, vertical or sloped) is not relevant to its definition (in contrary to IfcBeam and IfcColumn).

HISTORY New entity in IFC Release 2x2 Addendum.
IFC2x2 ADDENDUM CHANGE The entity IfcMember has been added. Upward compatibility for file based exchange is guaranteed.

Type Use Definition

IfcMember defines the occuurence of any member, common information about member types (or styles) is handled by IfcMemberType. The IfcMemberType (if present) may establish the common type name, usage (or predefined) type, common material layer set, common set of properties and common shape representations (using IfcRepresentationMap). The IfcMemberType is attached using the IfcRelDefinedByType.RelatingType objectified relationship and is accessible by the inverse IsDefinedBy attribute.

If no IfcMemberType is attached (i.e. if only occurrence information is given) the predefined type may be given by using the ObjectType attribute. Recommended values are 'member' (the default), 'brace', 'collar', 'member', 'post', 'purlin', 'rafter', 'stringer', 'strut'.

Property Set Use Definition

The property sets relating to the IfcMember 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 IfcMember are part of this IFC release:

Pset_MemberCommon: common property set for all member occurrences

Material Use Definition

The material of the IfcMember 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 IfcMemberType, defining the common attribute data for all occurrences of the same type. It is then accessible by the inverse IsDefinedBy relationship pointing to IfcMemberType.HasAssociations and via IfcRelAssociatesMaterial.RelatingMaterial to IfcMaterial or IfcMaterialList. If both are given, then the material directly assigned to IfcMember overrides the material assigned to IfcMemberType.

Quantity Use Definition

The quantities relating to the IfcMember 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:

Name	Description	Value Type
NominalLength	Total nominal length of the member, not taking into account any cut-out's or other processing features.	IfcQuantityLength
CrossSectionArea	Total area of the cross section (or profile) of the member. The exact definition and calculation rules depend on the method of measurement used.	IfcQuantityArea
OuterSurfaceArea	Total area of the extruded surfaces of the member (not taking into account the end cap areas), normally generated as perimeter * length.	IfcQuantityArea
TotalSurfaceArea	Total area of the member, normally generated as perimeter * length + 2 * cross section area.	IfcQuantityArea
GrossVolume	Total gross volume of the member, 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 member, 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 member 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 member without add-on parts, taking into account possible processing features (cut-out's, etc.) or openings and recesses.	IfcQuantityWeight

Containment Use Definition

The IfcMember, 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.

The IfcMember is placed within the project spatial hierarchy using the objectified relationship IfcRelContainedInSpatialStructure, referring to it by its inverse attribute SELF\IfcElement.ContainedInStructure. Subtypes of IfcSpatialStructureElement are valid spatial containers, with IfcBuildingStorey being the default container.
The IfcMember may be aggregated into an element assembly using the objectified relationship IfcRelAggregates, referring to it by its inverse attribute SELF\IfcObjectDefinition.Decomposes. Any subtype of IfcElement can be an element assembly, with IfcElementAssembly as a special focus subtype.

Geometry Use Definition

The geometric representation of IfcMember is given by the IfcProductDefinitionShape, allowing multiple geometric representations. Included are:

Local Placement

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.

Geometric Representations

Currently, the use of 'SweptSolid', 'Clipping', and 'MappedRepresentation' representations is supported. In addition the general representation types 'SurfaceModel', 'Brep', and 'BoundingBox' are allowed. The geometry use definition for 'BoundingBox', 'SurfaceModel' and 'Brep' is explained at IfcBuildingElement.

SweptSolid Representation

The standard geometric representation of IfcMember is defined using the 'SweptSolid' representation. 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 shall be supported
Profile: All subtypes of IfcParameterizedProfileDef and IfcArbitraryClosedProfileDef (including the subtype IfcArbitraryProfileDefWithVoids) shall be supported (exclusions need to be agreed upon by implementer agreements).
Extrusion: All extrusion directions shall be supported.

EXAMPLE: standard geometric representation.

The following interpretation of dimension parameter applies for rectangular members:

IfcRectangleProfileDef.YDim interpreted as member width

IfcRectangleProfileDef.XDim interpreted as member depth

The following interpretation of dimension parameter applies for circular members:

IfcCircleProfileDef Radius interpreted as member radius.

Use of IfcBooleanClippingResult between an IfcExtrudedAreaSolid and an IfcHalfSpaceSolid to create a clipped body.

Clipping Representation

The advanced geometric representation of IfcBeam is defined using the 'Clipping' geometry. 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).

EXAMPLE advanced geometric representation

Use of IfcBooleanClippingResult between an IfcExtrudedAreaSolid and an IfcHalfSpaceSolid to create a clipped body.

MappedRepresentation

In addition to the 'SweptSolid' and the 'Clipping' geometric representation of IfcMember also the 'MappedRepresentation' shall be supported as it allows for reusing the geometry definition of the member 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' and the 'Clipping' geometric representation, shall apply to the MappedRepresentation of the IfcRepresentationMap.

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	A
IfcRoot
1	GlobalId	IfcGloballyUniqueId	[1:1]	Assignment of a globally unique identifier within the entire software world.	X
2	OwnerHistory	IfcOwnerHistory	[1:1]	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.	X
3	Name	IfcLabel	[0:1]	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.	X
4	Description	IfcText	[0:1]	Optional description, provided for exchanging informative comments.	X
IfcObjectDefinition
	IsDecomposedBy	IfcRelDecomposes @RelatingObject	S[0:?]	Reference to the decomposition relationship, that allows this object to be the composition of other objects. An object can be decomposed by several other objects.	X
	Decomposes	IfcRelDecomposes @RelatedObjects	S[0:1]	References to the decomposition relationship, that allows this object to be a part of the decomposition. An object can only be part of a single decomposition (to allow hierarchical strutures only).	X
	HasAssociations	IfcRelAssociates @RelatedObjects	S[0:?]	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.	X
IfcObject
5	ObjectType	IfcLabel	[0:1]	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.	X
	IsDefinedBy	IfcRelDefines @RelatedObjects	S[0:?]	Set of relationships to type or property (statically or dynamically defined) information that further define the object. In case of type information, the associated IfcTypeObject contains the specific information (or type, or style), that is common to all instances of IfcObject referring to the same type.	X
IfcProduct
6	ObjectPlacement	IfcObjectPlacement	[0:1]	Placement of the product in space, the placement can either be absolute (relative to the world coordinate system), relative (relative to the object placement of another product), or constraint (e.g. relative to grid axes). It is determined by the various subtypes of IfcObjectPlacement, which includes the axis placement information to determine the transformation for the object coordinate system.	X
7	Representation	IfcProductRepresentation	[0:1]	Reference to the representations of the product, being either a representation (IfcProductRepresentation) or as a special case a shape representations (IfcProductDefinitionShape). The product definition shape provides for multiple geometric representations of the shape property of the object within the same object coordinate system, defined by the object placement.	X
IfcElement
8	Tag	-		This attribute is out of scope for this model view definition and shall not be set.
	ConnectedTo	IfcRelConnectsElements @RelatingElement	S[0:?]	Reference to the element connection relationship. The relationship then refers to the other element to which this element is connected to.
	HasOpenings	IfcRelVoidsElement @RelatingBuildingElement	S[0:?]	Reference to the Voids Relationship that creates an opening in an element. An element can incorporate zero-to-many openings.	X
	IsConnectionRealization	IfcRelConnectsWithRealizingElements @RealizingElements	S[0:?]	Reference to the connection relationship with realizing element. The relationship then refers to the realizing element which provides the physical manifestation of the connection relationship.	X
	ConnectedFrom	IfcRelConnectsElements @RelatedElement	S[0:?]	Reference to the element connection relationship. The relationship then refers to the other element that is connected to this element.	X
	ContainedInStructure	IfcRelContainedInSpatialStructure @RelatedElements	S[0:1]	Containment relationship to the spatial structure element, to which the element is primarily associated.	X
IfcBuildingElement
IfcMember

Definitions applying to AISC Model View

Instance diagram

A piece is major element of an assembly and is mapped to different IFC entity data types (IfcMember, IfcColumn, or IfcBeam) for its represenation depending on its position. Column is for a vertical steel element, Beam is for a horizontal steel member, and Member is for a diagonally placed element. There can be multiple pieces in an assembly, and one main piece that is identifed by a property attribute.

A piece may have attributes listed below should use Defines By Property Set (IfcRelDefinesByPropertyies) in order to represent required information items listed below and are described in the corresponding sections of this document.

Piece Identification

GUID
Part name
Piece mark
Indication mark
Main piece tag
Prelim mark
Bar code

Material Information

Material class
Material ID
Material certification
Material grade
Material type

Status Information

Status flags

Version

Version number

Quantity Information

Count

Finish/ Treatment

Surface treatment

Tolerance for Layout

Tolerance

Castellation

Castellation type
Castellation End Post Width 1
Castellation End Post Width 2
Castellation spacing
Castellation height
Castellation width
Castellation depth

Information Item Mapping

Steel Detailing Information	IFC Entity\Attribute	Note
Host Assembly	IfcRelAggregates
Critical end point	IfcDiscreteAccessory \ Representation
Angle of end cuts	IfcOpeningElement \ Representation
Location in Assembly	IfcProduct \ ObjectPlacement
Profile	IfcParameterizedProfileDef
Length	IfcExtrudedAreaSolid \ Depth

Concept usage

Properties on Occurrences

The Properties on Occurrences concept applies to this entity as shown in Table 17.

Property
AISC_EM11_Pset_PieceIdentification
AISC_EM11_Pset_ToleranceForLayout
AISC_EM11_Pset_Castellation
AISC_EM11_Pset_Material
AISC_EM11_Pset_StatusInformation
AISC_EM11_Pset_VersionInformation

Table 17 — IfcMember Properties on Occurrences

Exchange
Import	O
Export	O

Placement

The Placement concept applies to this entity.

Exchange
Import	R
Export	R

Body Geometry

The Body Geometry concept applies to this entity.

Exchange
Import	R
Export	R

Concept alternates

Body Profile Extruded Area Solid

The Body Profile Extruded Area Solid concept applies to this entity.

Exchange
Import	O
Export	O

Mapped Geometry

The Mapped Geometry concept applies to this entity.

Body Brep Geometry PolyLoop

The Body Brep Geometry PolyLoop concept applies to this entity.

Exchange
Import	O
Export	O

Feature Substraction

The Feature Substraction concept applies to this entity as shown in Table 18.

FeatureObjectType	Description
BoltHole	Represents an instance of Bolt Hole
SlotHole	Represents an instance of a Slot Hole
Cope	Represents an instance of a Cope
Opening	Represents an instance of an Opening
SkewedEnd	Represents an instance of a Skewed End, which has two axis of rotation
WeldPreparation	Represents an instance of a Weld Preparation
TubeChamfer	Represents an instance of a Tube Chamfer
TubeSaddle	Represents an instance of a Tube Saddle
TubeEdgeSaddle	Represents an instance of a Tube Edge Saddle
TubeCrossingSaddle	Represents an instance of a Tube Crossing Saddle
TubeHoleSetIn	Represents an instance of a Tube Hole Set In
TubeHoleSetOut	Represents an instance of a Tube Hole Set Out
TubeMitreHole	Represents an instance of a Tube Hole Mitre Hole
TubeMitreSaddle	Represents an instance of a Tube Hole Mitre Saddle
TubeOblongHole	Represents an instance of a Tube Oblong Hole
TubeOffshoreSaddle	Represents an instance of a Tube Offshore Saddle
TubeOffshoreChamfer	Represents an instance of a Tube Offshore Chamfer

Table 18 — IfcMember Feature Substraction

Exchange
Import	O
Export	O

Element Decomposition

The Element Decomposition concept applies to this entity as shown in Table 19.

RelatedObjects	Description
IfcPlate	Represents each plate for 3-Plate structural piece

Table 19 — IfcMember Element Decomposition

W or I shaped structural steel piece (column, beam or member) can be assembled with three plates. IfcRelAggregate\RelatedObject should refer to IfcBeam, IfcColumn or IfcMember, and IfcRelAggregate\RelatedObject should refer to IfcPlate

Exchange
Import	O
Export	O

Material Solid

The Material Solid concept applies to this entity.

Exchange
Import	O
Export	O

Quantities on Occurrences

The Quantities on Occurrences concept applies to this entity as shown in Table 20.

Qset	Quantity	Description
AISC_EM11_Qto_Quantity	SameTypeCount	Number of assemblies with same assembly mark. Used on occuerrence, even though it should be used for type count for implementation convenience

Table 20 — IfcMember Quantities on Occurrences

Exchange
Import	O
Export	O

Concept inheritance

#	Concept	Model View
IfcMember
	Properties on Occurrences	AISC Model View
	Placement	AISC Model View
	Body Geometry	AISC Model View
	Feature Substraction	AISC Model View
	Element Decomposition	AISC Model View
	Material Solid	AISC Model View
	Quantities on Occurrences	AISC Model View

Formal representations

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);

END_ENTITY;

 EXPRESS-G diagram

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