IfcElementAssembly

Natural language names
zusammengesetztes Element
Element Assembly
Assemblage d'éléments
Change log
ItemSPFXMLChangeDescription
4.0.0.0
    IfcElementAssembly
      OwnerHistoryMODIFIEDInstantiation changed to OPTIONAL.
      PredefinedTypeMODIFIEDInstantiation changed to OPTIONAL.
4.0.1.0
    IfcElementAssembly
      HasCoveringsADDED
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 R
9AssemblyPlace- This attribute is out of scope for this model view definition and shall not be set.
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
#AttributeTypeCardinalityDescriptionR
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.
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.
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
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
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.
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
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
IfcElementAssembly
9AssemblyPlace- This attribute is out of scope for this model view definition and shall not be set.
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 Reference View

 Instance diagram


Concept usage

Object Typing

The Object Typing concept template applies to this entity as shown in Table 22.

HasTypeRelatingType
IfcElementAssemblyType

Table 22 — IfcElementAssembly Object Typing



Property Sets for Objects

The Property Sets for Objects concept template applies to this entity as shown in Table 23.

PsetNameProperties
Pset_ElementAssemblyCommon
TemplatePropertyNameValue
Single ValueReferenceIfcLabel
Single ValueStatusIfcLabel

Table 23 — IfcElementAssembly Property Sets for Objects



Element Decomposition

The Element Decomposition concept applies to this entity.

Any instance of IfcElementAssembly shall be a composite, defining an assembly. Therefore the inverse relationship IsDecomposedBy shall be used by at least one instance of IfcRelAggregates.



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="9c1f586b-c6cc-496c-b9fc-81e5cb1f9523" name="IfcElementAssembly" status="sample" applicableRootEntity="IfcElementAssembly">
  <Applicability uuid="00000000-0000-0000-0000-000000000000" status="sample">
    <Template ref="1cc5d759-a002-4eb2-ad6d-eed8c557182c" />
    <TemplateRules operator="and" />
  </Applicability>
  <Concepts>
    <Concept uuid="97c28ab0-d880-440c-b55c-8f3a5bd3866e" name="Object Typing" status="sample" override="false">
      <Template ref="35a2e10e-20df-40f4-ab2f-dacf0a6744f4" />
      <TemplateRules operator="and">
        <TemplateRule Parameters="RelatingType=IfcElementAssemblyType;" />
      </TemplateRules>
    </Concept>
    <Concept uuid="1a5e4b1c-4078-49cd-96c0-b504c9e384b7" name="Property Sets for Objects" status="sample" override="false">
      <Template ref="f74255a6-0c0e-4f31-84ad-24981db62461" />
      <TemplateRules operator="and">
        <TemplateRule Parameters="PsetName=Pset_ElementAssemblyCommon;" />
      </TemplateRules>
    </Concept>
    <Concept uuid="9c50cefe-63ef-4818-a0d1-4a60d624607f" name="Element Decomposition" status="sample" override="false">
      <Template ref="8a27c15a-c4ea-4ca9-8cce-7fbba1c9bce0" />
    </Concept>
  </Concepts>
</ConceptRoot>
Concept inheritance

#ConceptTemplateModel View
IfcRoot
IdentitySoftware IdentityReference View
Revision ControlRevision ControlReference View
IfcObjectDefinition
ClassificationClassificationReference View
IfcObject
Object User IdentityObject User IdentityReference View
Object Predefined TypeObject Predefined TypeReference View
Property Sets for ObjectsProperty Sets with OverrideReference View
IfcElement
Product Local PlacementProduct Local PlacementReference View
CoG GeometryCoG GeometryReference View
Box GeometryBox GeometryReference View
Body Solid Geometry GeneralBody Geometry GeneralReference View
Body Tessellation GeometryBody Tessellation GeometryReference View
Body SweptSolid PolyCurve GeometryBody SweptSolid PolyCurve GeometryReference View
Mapped GeometryMapped GeometryReference View
Product Geometry LayerProduct Geometry LayerReference View
Product Geometry ColourProduct Geometry ColourReference View
Spatial ContainmentSpatial ContainmentReference View
Element CompositionElement CompositionReference View
Element VoidingElement VoidingReference View
Material SingleMaterial Single for Objects with OverrideReference View
Material ConstituentMaterial Constituent Set with OverrideReference View
ClassificationClassification for Objects with OverrideReference View
IfcElementAssembly
Object TypingObject TypingReference View
Property Sets for ObjectsProperty Sets for ObjectsReference View
Element DecompositionElement DecompositionReference View
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="PredefinedType" type="ifc:IfcElementAssemblyTypeEnum" use="optional"/>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>
EXPRESS Specification
ENTITY IfcElementAssembly
 SUBTYPE OF (IfcElement);
  AssemblyPlace : OPTIONAL IfcStrippedOptional;
  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