IfcElementAssembly

Natural language names
zusammengesetztes Element
Element Assembly
Assemblage d'éléments
Change log
ItemSPFXMLChangeDescription
IFC2x3 to IFC4
    IfcElementAssembly
      OwnerHistoryMODIFIEDInstantiation changed to OPTIONAL.
      PredefinedTypeMODIFIEDInstantiation changed to OPTIONAL.
IFC4 Addendum 1
    IfcElementAssembly
      HasCoveringsADDED
IFC4x2 DRAFT 1
    IfcElementAssembly
      PositionedRelativeToADDED
Semantic definitions at the entity
Entity definition

The IfcElementAssembly represents complex element assemblies aggregated from several elements, such as discrete elements, building elements, or other elements.

EXAMPLE Steel construction assemblies, such as trusses and different kinds of frames, can be represented by the IfcElementAssembly entity. Other examples include slab fields aggregated from a number of precast concrete slabs or reinforcement units made from several reinforcement bars. Also bathroom units, staircase sections and other premanufactured or precast elements are examples of the general IfcElementAssembly entity
NOTE  The IfcElementAssembly is a general purpose entity that is required to be decomposed. Also other subtypes of IfcElement can be decomposed, with some dedicated entities such as IfcWallElementedCase and IfcSlabElementedCase.

The assembly structure can be nested, i.e. an IfcElementAssembly could be an aggregated part within another IfcElementAssembly.

NOTE  View definitions and/or implementer agreements may restrict the number of allowed levels of nesting.

The geometry of an IfcElementAssembly is generally formed from its components, in which case it does not need to have an explicit geometric representation. In some cases it may be useful to also expose an own explicit representation of the aggregate.

NOTE  View definitions or implementer agreements may further constrain the applicability of certain shape representations at the IfcElementAssembly in respect of the shape representations of its parts.
HISTORY  New entity in IFC2x2.

Informal Propositions:

  1. The IfcElementAssembly shall have an aggregation relationship to the contained parts, i.e. the (INV) IsDecomposedBy relationship shall be utilzed.
Attribute definitions
#AttributeTypeCardinalityDescription G
9AssemblyPlaceIfcAssemblyPlaceEnum? A designation of where the assembly is intended to take place defined by an Enum.X
10PredefinedTypeIfcElementAssemblyTypeEnum? Predefined generic types for a element assembly that are specified in an enumeration. There might be property sets defined specifically for each predefined type.
IFC4 CHANGE  The attribute has been changed to be optional.
X
Formal Propositions
RuleDescription
CorrectPredefinedTypeEither the PredefinedType attribute is unset (e.g. because an IfcElementAssemblyType is associated), or the inherited attribute ObjectType shall be provided, if the PredefinedType is set to USERDEFINED.
CorrectTypeAssignedEither there is no element assembly type object associated, i.e. the IsTypedBy inverse relationship is not provided, or the associated type object has to be of type IfcElementAssemblyType.
Inherited definitions from supertypes
Entity inheritance IfcElement IfcProduct IfcObject IfcObjectDefinition IfcRoot
Attribute inheritance
#AttributeTypeCardinalityDescriptionG
IfcRoot
1GlobalIdIfcGloballyUniqueId Assignment of a globally unique identifier within the entire software world. X
2OwnerHistoryIfcOwnerHistory? 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.
X
3NameIfcLabel? 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
4DescriptionIfcText? Optional description, provided for exchanging informative comments.X
IfcObjectDefinition
HasAssignmentsIfcRelAssigns
@RelatedObjects
S[0:?]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.X
NestsIfcRelNests
@RelatedObjects
S[0:1]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.
X
IsNestedByIfcRelNests
@RelatingObject
S[0:?]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.
X
HasContextIfcRelDeclares
@RelatedDefinitions
S[0:1]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.
X
IsDecomposedByIfcRelAggregates
@RelatingObject
S[0:?]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.
X
DecomposesIfcRelAggregates
@RelatedObjects
S[0:1]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.
X
HasAssociationsIfcRelAssociates
@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
5ObjectTypeIfcLabel? 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
IsDeclaredByIfcRelDefinesByObject
@RelatedObjects
S[0:1]Link to the relationship object pointing to the declaring object that provides the object definitions for this object occurrence. The declaring object has to be part of an object type decomposition. The associated IfcObject, or its subtypes, contains the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes.
IFC4 CHANGE  New inverse relationship, change made with upward compatibility for file based exchange.
X
DeclaresIfcRelDefinesByObject
@RelatingObject
S[0:?]Link to the relationship object pointing to the reflected object(s) that receives the object definitions. The reflected object has to be part of an object occurrence decomposition. The associated IfcObject, or its subtypes, provides the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes.
IFC4 CHANGE  New inverse relationship, change made with upward compatibility for file based exchange.
X
IsTypedByIfcRelDefinesByType
@RelatedObjects
S[0:1]Set of relationships to the object type that provides the type definitions for this object occurrence. The then associated IfcTypeObject, or its subtypes, contains the specific information (or type, or style), that is common to all instances of IfcObject, or its subtypes, referring to the same type.
IFC4 CHANGE  New inverse relationship, the link to IfcRelDefinesByType had previously be included in the inverse relationship IfcRelDefines. Change made with upward compatibility for file based exchange.
X
IsDefinedByIfcRelDefinesByProperties
@RelatedObjects
S[0:?]Set of relationships to property set definitions attached to this object. Those statically or dynamically defined properties contain alphanumeric information content that further defines the object.
IFC4 CHANGE  The data type has been changed from IfcRelDefines to IfcRelDefinesByProperties with upward compatibility for file based exchange.
X
IfcProduct
6ObjectPlacementIfcObjectPlacement? 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
7RepresentationIfcProductRepresentation? 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
ReferencedByIfcRelAssignsToProduct
@RelatingProduct
S[0:?]Reference to the IfcRelAssignsToProduct relationship, by which other products, processes, controls, resources or actors (as subtypes of IfcObjectDefinition) can be related to this product.X
PositionedRelativeToIfcRelPositions
@RelatedProducts
S[0:1]X
IfcElement
8TagIfcIdentifier? The tag (or label) identifier at the particular instance of a product, e.g. the serial number, or the position number. It is the identifier at the occurrence level.X
FillsVoidsIfcRelFillsElement
@RelatedBuildingElement
S[0:1]Reference to the IfcRelFillsElement Relationship that puts the element as a filling into the opening created within another element. X
ConnectedToIfcRelConnectsElements
@RelatingElement
S[0:?]Reference to the element connection relationship. The relationship then refers to the other element to which this element is connected to. X
IsInterferedByElementsIfcRelInterferesElements
@RelatedElement
S[0:?]Reference to the interference relationship to indicate the element that is interfered. The relationship, if provided, indicates that this element has an interference with one or many other elements.
NOTE  There is no indication of precedence between IsInterferedByElements and InterferesElements.
IFC4 CHANGE New inverse relationship.
X
InterferesElementsIfcRelInterferesElements
@RelatingElement
S[0:?]Reference to the interference relationship to indicate the element that interferes. The relationship, if provided, indicates that this element has an interference with one or many other elements.
NOTE  There is no indication of precedence between IsInterferedByElements and InterferesElements.
IFC4 CHANGE New inverse relationship.
X
HasProjectionsIfcRelProjectsElement
@RelatingElement
S[0:?]Projection relationship that adds a feature (using a Boolean union) to the IfcBuildingElement.X
ReferencedInStructuresIfcRelReferencedInSpatialStructure
@RelatedElements
S[0:?]Reference relationship to the spatial structure element, to which the element is additionally associated. This relationship may not be hierarchical, an element may be referenced by zero, one or many spatial structure elements.
IFC2x3 CHANGE  The inverse attribute has been added with upward compatibility for file based exchange.
X
HasOpeningsIfcRelVoidsElement
@RelatingBuildingElement
S[0:?]Reference to the IfcRelVoidsElement relationship that creates an opening in an element. An element can incorporate zero-to-many openings. For each opening, that voids the element, a new relationship IfcRelVoidsElement is generated. X
IsConnectionRealizationIfcRelConnectsWithRealizingElements
@RealizingElements
S[0:?]Reference to the connection relationship with realizing element. The relationship, if provided, assigns this element as the realizing element to the connection, which provides the physical manifestation of the connection relationship. X
ProvidesBoundariesIfcRelSpaceBoundary
@RelatedBuildingElement
S[0:?]Reference to space boundaries by virtue of the objectified relationship IfcRelSpaceBoundary. It defines the concept of an element bounding spaces. X
ConnectedFromIfcRelConnectsElements
@RelatedElement
S[0:?]Reference to the element connection relationship. The relationship then refers to the other element that is connected to this element. X
ContainedInStructureIfcRelContainedInSpatialStructure
@RelatedElements
S[0:1]Containment relationship to the spatial structure element, to which the element is primarily associated. This containment relationship has to be hierachical, i.e. an element may only be assigned directly to zero or one spatial structure. X
HasCoveringsIfcRelCoversBldgElements
@RelatingBuildingElement
S[0:?]Reference to IfcCovering by virtue of the objectified relationship IfcRelCoversBldgElement. It defines the concept of an element having coverings associated.X
IfcElementAssembly
9AssemblyPlaceIfcAssemblyPlaceEnum? A designation of where the assembly is intended to take place defined by an Enum.X
10PredefinedTypeIfcElementAssemblyTypeEnum? Predefined generic types for a element assembly that are specified in an enumeration. There might be property sets defined specifically for each predefined type.
IFC4 CHANGE  The attribute has been changed to be optional.
X
Definitions applying to General Usage

 Instance diagram


Concept usage

Object Typing

The Object Typing concept template applies to this entity as shown in Table 55.

HasTypeRelatingType
IfcElementAssemblyType

Table 55 — IfcElementAssembly Object Typing



Aggregation

The Aggregation concept template applies to this entity as shown in Table 56.

Table 56 — IfcElementAssembly Aggregation

The IfcElementAssembly shall represent an aggregate, i.e. it should have other elements, being subtypes of IfcElement, as contained (sub)parts. The table above only represents a selection of subtypes of IfcElement that are legitimate as parts in an IfcElementAssembly

Figure 156 illustrates spatial containment and element aggregation relationships.

containment relationships

Figure 156 — Element assembly containment



Spatial Containment

The Spatial Containment concept template applies to this entity as shown in Table 57.

RelatingStructureDescription
IfcBuildingStoreyDefault spatial container
IfcBuildingSpatial container for element assemblies not assignable to a building storey
IfcSiteSpatial container for element assemblies that are placed on site (outside of building)

Table 57 — IfcElementAssembly Spatial Containment

The IfcElementAssembly should have a relationship for its containment in the hierachical spatial structure of the project. Only if the IfcElementAssembly is itself a part of another assembly this relationship should be omitted.



mvdXML Specification
<?xml version="1.0"?>
<ConceptRoot xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" uuid="384d756a-23ce-484a-bd4b-493193adf652" name="IfcElementAssembly" status="sample" applicableRootEntity="IfcElementAssembly">
  <Applicability uuid="00000000-0000-0000-0000-000000000000" status="sample">
    <Template ref="9321d85d-48d1-4e2c-8b37-a2050dfd2487" />
    <TemplateRules operator="and" />
  </Applicability>
  <Concepts>
    <Concept uuid="4a86d021-4a02-4211-b5f5-7d31368959cc" name="Object Typing" status="sample" override="false">
      <Template ref="35a2e10e-20df-40f4-ab2f-dacf0a6744f4" />
      <TemplateRules operator="and">
        <TemplateRule Parameters="RelatingType[Type]='IfcElementAssemblyType'" />
      </TemplateRules>
    </Concept>
    <Concept uuid="329387d6-69b6-4777-be2e-31e0c2ace094" name="Aggregation" status="sample" override="false">
      <Template ref="02eefcc6-b26c-4f20-9c7c-c30ae74eb9a9" />
      <TemplateRules operator="and">
        <TemplateRule Description="Members within the assembly." Parameters="" />
        <TemplateRule Description="Plates within the assembly." Parameters="" />
        <TemplateRule Description="Components within the assembly." Parameters="" />
      </TemplateRules>
    </Concept>
    <Concept uuid="4c2da84e-2930-4429-9e40-0b7ccbf1c166" name="Spatial Containment" status="sample" override="false">
      <Template ref="d9a3f822-0014-4bc2-8d94-9d9067759045" />
      <TemplateRules operator="and">
        <TemplateRule Description="Default spatial container" Parameters="RelatingStructure[Type]='IfcBuildingStorey'" />
        <TemplateRule Description="Spatial container for element assemblies not assignable to a building storey" Parameters="RelatingStructure[Type]='IfcBuilding'" />
        <TemplateRule Description="Spatial container for element assemblies that are placed on site (outside of building)" Parameters="RelatingStructure[Type]='IfcSite'" />
      </TemplateRules>
    </Concept>
  </Concepts>
</ConceptRoot>
Concept inheritance

#ConceptTemplateModel View
IfcRoot
IdentitySoftware IdentityGeneral Usage
Revision ControlRevision ControlGeneral Usage
IfcObjectDefinition
Classification AssociationClassification AssociationGeneral Usage
IfcObject
Object User IdentityObject User IdentityGeneral Usage
Object Predefined TypeObject Predefined TypeGeneral Usage
Property Sets with OverrideProperty Sets with OverrideGeneral Usage
IfcProduct
Product PlacementProduct PlacementGeneral Usage
Product Geometric RepresentationProduct Geometric RepresentationGeneral Usage
IfcElement
Property Sets for ObjectsProperty Sets for ObjectsGeneral Usage
Product Local PlacementProduct Local PlacementGeneral Usage
CoG GeometryCoG GeometryGeneral Usage
Box GeometryBox GeometryGeneral Usage
FootPrint GeometryFootPrint GeometryGeneral Usage
Body SurfaceOrSolidModel GeometryBody SurfaceOrSolidModel GeometryGeneral Usage
Body SurfaceModel GeometryBody SurfaceModel GeometryGeneral Usage
Body Tessellation GeometryBody Tessellation GeometryGeneral Usage
Body Brep GeometryBody Brep GeometryGeneral Usage
Body AdvancedBrep GeometryBody AdvancedBrep GeometryGeneral Usage
Body CSG GeometryBody CSG GeometryGeneral Usage
Mapped GeometryMapped GeometryGeneral Usage
Element VoidingElement VoidingGeneral Usage
Element ProjectingElement ProjectingGeneral Usage
Linear PlacementProduct Linear PlacementGeneral Usage
IfcElementAssembly
Object TypingObject TypingGeneral Usage
AggregationAggregationGeneral Usage
Spatial ContainmentSpatial ContainmentGeneral Usage
Examples
Formal representations
XML Specification
 <xs:element name="IfcElementAssembly" type="ifc:IfcElementAssembly" substitutionGroup="ifc:IfcElement" nillable="true"/>
 <xs:complexType name="IfcElementAssembly">
  <xs:complexContent>
   <xs:extension base="ifc:IfcElement">
    <xs:attribute name="AssemblyPlace" type="ifc:IfcAssemblyPlaceEnum" use="optional"/>
    <xs:attribute name="PredefinedType" type="ifc:IfcElementAssemblyTypeEnum" use="optional"/>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>
EXPRESS Specification
ENTITY IfcElementAssembly
 SUBTYPE OF (IfcElement);
  AssemblyPlace : OPTIONAL IfcAssemblyPlaceEnum;
  PredefinedType : OPTIONAL IfcElementAssemblyTypeEnum;
 WHERE
  CorrectPredefinedType : NOT(EXISTS(PredefinedType)) OR
(PredefinedType <> IfcElementAssemblyTypeEnum.USERDEFINED) OR
((PredefinedType = IfcElementAssemblyTypeEnum.USERDEFINED) AND EXISTS (SELF\IfcObject.ObjectType));
  CorrectTypeAssigned : (SIZEOF(IsTypedBy) = 0) OR
('IFCPRODUCTEXTENSION.IfcElementAssemblyType' IN TYPEOF(SELF\IfcObject.IsTypedBy[1].RelatingType));
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

Link to this page  Link to this page