Composant d'élément

An element component is a representation for minor items included in, added to or connecting to or between elements, which usually are not of interest from the overall building structure viewpoint. However, these small parts may have vital and load carrying functions within the construction. These items do not provide any actual space boundaries. Typical examples of IfcElementComponents include different kinds of fasteners and various accessories.

One or several instances of subtypes of IfcElementComponent should always be accompanied by a defining instance of a respective subtype of IfcElementComponentType. The type object holds shape and material information.

HISTORY  New entity in IFC2x2

It is often desirable to model a number of same-shaped element components by means of a single occurrence object, e.g. several bolts within a connection or a row of reinforcement elements. In this IFC release, this is possible by means of multiple mapped representation as documented below.

To express the multiplicity of element components also on a higher semantic level, a Qto_ElementComponentPatternQuantities should be provided via IfcRelDefinesByProperties and contain the number of pieces which are placed by a single IfcElementComponent instance.

Symbolic Representation

A symbolic representation is defined for a row of components or several rows of components within a single instance of IfcElementComponent. Such rows or arrays may contain possibly large numbers of individual pieces. The product definition shape consists of an IfcShapeRepresentation with the attribute values

and one or several curves as geometric items. The curves represent where reference points of the pieces are located. For example, such reference points may be at the heads of mechanical fasteners or at the starting point of the extrusion axis of reinforcement bars. In case of straight components (bolts, nails, staples, straight reinforcement bars, or similar), the local placement of the IfcElementComponent shall be located and oriented such that the local z axis is parallel with the axes of the components. A Qto_ElementComponentPatternQuantities should denote the count of pieces in the row or array and their spacing.

Common Use Definitions

The following concepts are inherited at supertypes:

 Instance diagram

Property Sets for Objects

The Property Sets for Objects concept applies to this entity as shown in Table 227.

Table 227 — IfcElementComponent Property Sets for Objects

Mapped Geometry

The Mapped Geometry concept applies to this entity.

The mapped item, IfcMappedItem, should be used if appropriate as it allows for reusing the geometry definition of a type at all occurrences of the same type.

A single instance of a subtype of IfcElementComponent can stand for several actual element components at once. In this case, the IfcShapeRepresentation contains as many mapped items as there are element components combined within this occurrence object.


EXAMPLE  Figure 238 illustrates multiple components modeled as a single occurrence object (here: IfcFastener)

Figure 238 — Element component mapped representation


Representation identifier and type are the same as in single mapped representation. The number of mapped items in the representation corresponds with the count of element components in the IfcElementQuantity.

XSD Specification:

 <xs:element name="IfcElementComponent" type="ifc:IfcElementComponent" abstract="true" substitutionGroup="ifc:IfcElement" nillable="true"/>
 <xs:complexType name="IfcElementComponent" abstract="true">
   <xs:extension base="ifc:IfcElement"/>

EXPRESS Specification:

ENTITY IfcElementComponent
ABSTRACT SUPERTYPE OF(ONEOF(IfcBuildingElementPart, IfcDiscreteAccessory, IfcFastener, IfcMechanicalFastener, IfcReinforcingElement, IfcVibrationIsolator))
SUBTYPE OF IfcElement;

Link to EXPRESS-G diagram EXPRESS-G diagram

Inheritance Graph:

ENTITY IfcElementComponent
GlobalId : IfcGloballyUniqueId;
OwnerHistory : OPTIONAL IfcOwnerHistory;
Name : OPTIONAL IfcLabel;
Description : OPTIONAL IfcText;
ENTITY IfcObjectDefinition
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 IfcLabel;
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;
ReferencedBy : SET OF IfcRelAssignsToProduct FOR RelatingProduct;
ENTITY IfcElement
Tag : OPTIONAL IfcIdentifier;
FillsVoids : SET [0:1] OF IfcRelFillsElement FOR RelatedBuildingElement;
ConnectedTo : SET OF IfcRelConnectsElements FOR RelatingElement;
IsInterferedByElements : SET OF IfcRelInterferesElements FOR RelatedElement;
InterferesElements : SET OF IfcRelInterferesElements FOR RelatingElement;
HasProjections : SET OF IfcRelProjectsElement FOR RelatingElement;
ReferencedInStructures : SET OF IfcRelReferencedInSpatialStructure FOR RelatedElements;
HasOpenings : SET OF IfcRelVoidsElement FOR RelatingBuildingElement;
IsConnectionRealization : SET OF IfcRelConnectsWithRealizingElements FOR RealizingElements;
ProvidesBoundaries : SET OF IfcRelSpaceBoundary FOR RelatedBuildingElement;
ConnectedFrom : SET OF IfcRelConnectsElements FOR RelatedElement;
ContainedInStructure : SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements;
ENTITY IfcElementComponent

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