IFC 4.3.x development

6.1.3.53 IfcWallElementedCase

Change log

IFC4

added

6.1.3.53.1 Semantic definitions at the entity

The IfcWallElementedCase defines a wall with certain constraints for the provision of its components. The IfcWallElementedCase handles all cases of walls, that are decomposed into parts:

Parts within the decomposition are usually be of type:

EXAMPLE Elemented walls may extend the concepts of standard walls with the following features, as shown in Figure 1, including the IfcRelConnectsWithRealizingElements relationship to define fasteners and accessories.

"voiding"

HISTORY  New entity in IFC4.

Formal Propositions

HasDecomposition

A valid instance of IfcWallElementedCase has to have parts in a decomposition hierarchy.

# Attribute Type Description
IfcRoot
1 GlobalId IfcGloballyUniqueId Assignment of a globally unique identifier within the entire software world.
2 OwnerHistory OPTIONAL IfcOwnerHistory 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.
3 Name OPTIONAL IfcLabel 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.
4 Description OPTIONAL IfcText Optional description, provided for exchanging informative comments.
IfcObjectDefinition
HasAssignments SET [0:?] OF IfcRelAssigns FOR RelatedObjects 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.
Nests SET [0:1] OF IfcRelNests FOR RelatedObjects 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.
IsNestedBy SET [0:?] OF IfcRelNests FOR RelatingObject 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.
HasContext SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions 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.
IsDecomposedBy SET [0:?] OF IfcRelAggregates FOR RelatingObject 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.
Decomposes SET [0:1] OF IfcRelAggregates FOR RelatedObjects 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.
HasAssociations SET [0:?] OF IfcRelAssociates FOR RelatedObjects 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.
IfcObject
5 ObjectType OPTIONAL IfcLabel 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.
IsDeclaredBy SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects 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.
Declares SET [0:?] OF IfcRelDefinesByObject FOR RelatingObject 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.
IsTypedBy SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects 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.
IsDefinedBy SET [0:?] OF IfcRelDefinesByProperties FOR RelatedObjects 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.
IfcProduct
6 ObjectPlacement OPTIONAL IfcObjectPlacement 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.
7 Representation IfcProductDefinitionShape 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.
ReferencedBy SET [0:?] OF IfcRelAssignsToProduct FOR RelatingProduct Reference to the IfcRelAssignsToProduct relationship, by which other products, processes, controls, resources or actors (as subtypes of IfcObjectDefinition) can be related to this product.
PositionedRelativeTo SET [0:1] OF IfcRelPositions FOR RelatedProducts
ReferencedInStructures SET [0:?] OF IfcRelReferencedInSpatialStructure FOR RelatedElements
IfcElement
8 Tag OPTIONAL IfcIdentifier 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.
FillsVoids SET [0:1] OF IfcRelFillsElement FOR RelatedBuildingElement Reference to the IfcRelFillsElement Relationship that puts the element as a filling into the opening created within another element.
ConnectedTo SET [0:?] OF IfcRelConnectsElements FOR RelatingElement Reference to the element connection relationship. The relationship then refers to the other element to which this element is connected to.
IsInterferedByElements SET [0:?] OF IfcRelInterferesElements FOR RelatedElement 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.
InterferesElements SET [0:?] OF IfcRelInterferesElements FOR RelatingElement 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.
HasProjections SET [0:?] OF IfcRelProjectsElement FOR RelatingElement Projection relationship that adds a feature (using a Boolean union) to the IfcBuildingElement.
HasOpenings SET [0:?] OF IfcRelVoidsElement FOR RelatingBuildingElement 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.
IsConnectionRealizationSET [0:?] OF IfcRelConnectsWithRealizingElements FOR RealizingElementsReference 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.
ProvidesBoundaries SET [0:?] OF IfcRelSpaceBoundary FOR RelatedBuildingElement Reference to space boundaries by virtue of the objectified relationship IfcRelSpaceBoundary. It defines the concept of an element bounding spaces.
ConnectedFrom SET [0:?] OF IfcRelConnectsElements FOR RelatedElement Reference to the element connection relationship. The relationship then refers to the other element that is connected to this element.
ContainedInStructure SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements 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.
HasCoverings SET [0:?] OF IfcRelCoversBldgElements FOR RelatingBuildingElement Reference to IfcCovering by virtue of the objectified relationship IfcRelCoversBldgElement. It defines the concept of an element having coverings associated.
HasSurfaceFeatures INVALID Reference to the IfcRelAdheresToElement relationship that adheres a IfcSurfaceFeature to an element. An element can incorporate zero-to-many surface features in one relationship.
IfcBuiltElement
IfcWall
9 PredefinedType OPTIONAL IfcWallTypeEnum Predefined generic type for a wall that is specified in an enumeration. There may be a property set given specifically for the predefined types.

> NOTE  The PredefinedType shall only be used, if no IfcWallType is assigned, providing its own _IfcWallType.PredefinedType_.

> IFC4 CHANGE The attribute has been added at the end of the entity definition.

6.1.3.53.1 Entity inheritance

dot_inheritance IfcWallElementedCase IfcWallElementedCase IfcWall IfcWall IfcWallElementedCase->IfcWall IfcWallStandardCase IfcWallStandardCase IfcWallStandardCase->IfcWall IfcBuiltElement IfcBuiltElement IfcWall->IfcBuiltElement IfcBuiltElement_children 29 more... IfcBuiltElement_children->IfcBuiltElement IfcElement IfcElement IfcBuiltElement->IfcElement IfcElement_children 10 more... IfcElement_children->IfcElement IfcProduct IfcProduct IfcElement->IfcProduct IfcProduct_children 8 more... IfcProduct_children->IfcProduct IfcObject IfcObject IfcProduct->IfcObject IfcObject_children 5 more... IfcObject_children->IfcObject IfcObjectDefinition IfcObjectDefinition IfcObject->IfcObjectDefinition IfcContext IfcContext IfcContext->IfcObjectDefinition IfcRoot IfcRoot IfcObjectDefinition->IfcRoot IfcTypeObject IfcTypeObject IfcTypeObject->IfcObjectDefinition IfcPropertyDefinition IfcPropertyDefinition IfcPropertyDefinition->IfcRoot IfcRelationship IfcRelationship IfcRelationship->IfcRoot

6.1.3.53.2 Definitions applying to General Usage

6.1.3.53.2.1 Axis 2D Geometry

The wall axis is represented by a two-dimensional open curve within a particular shape representation. The 'Axis' shape representation is only used to locate the material layer set along the axis, if the IfcMaterialLayerSetUsgae is applied to the IfcWall. In this case, the wall axis is used to apply the material layer set usage parameter to the wall geometry.

 

straight wall axis
EXAMPLE  Figure 279 illustrates an axis representation for a straight wall. In case of a straight wall, the set of items shall include a single geometric representation item of type IfcPolyline or IfcTrimmedCurve with the BasisCurve being an IfcLine. The IfcPolyline or IfcTrimmedCurve shall be parallel (here in a special case co-linear) to the x-axis of the object coordinate system. The direction shall be identical to the direction of the x-axis.

Figure 279 — Wall axis straight

 
curved wall axis
EXAMPLE  Figure 280 illustrates an axis representation for a curved wall. In case of a curved wall, the set of items shall include a single geometric representation item of type IfcTrimmedCurve. The curve shall have a BasisCurve of type IfcCircle. The tangent of the IfcTrimmedCurve shall be parallel at start to the x-axis of the object coordinate system. The direction shall be identical to the direction of the x-axis.

Figure 280 — Wall axis curved

 
Items Identifier Type
'IfcBoundedCurve''Axis' 'Curve2D'

6.1.3.53.2.2 Body AdvancedBrep Geometry

An IfcElement (so far no further constraints are defined at the level of its subtypes or by view definitions) may be represented as a single or multiple boundary representation models, which include advanced surfaces, usually refered to as NURBS surfaces. The 'AdvancedBrep' representation allows for the representation of complex free-form element shape.

NOTE  View definitions or implementer agreements may restrict or disallow the use of 'AdvancedBrep' geometry.

6.1.3.53.2.3 Body Brep Geometry

Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a single or multiple Boundary Representation models (which are restricted to be faceted Brep's with or without voids). The Brep representation allows for the representation of complex element shape.

 

Brep representation
EXAMPLE  As shown in Figure 150, the Brep representation is given by an IfcShapeRepresentation, which includes one or more items, all of type IfcFacetedBrep. In some cases it may be useful to also expose a simple representation as a bounding box representation of the same complex shape.

Figure 150 — Building element body boundary representation

 

6.1.3.53.2.4 Body CSG Geometry

Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented a CSG primitive or CSG tree. The CSG representation allows for the representation of complex element shape.

NOTE  View definitions or implementer agreements may restrict or disallow the use of 'CSG' geometry.

6.1.3.53.2.5 Body Clipping Geometry

The following additional constraints apply to the 'SweptSolid' representation, when an IfcMaterialLayerSetUsage is assigned to the IfcSlab:

  • Solid: see standard geometric representation
  • Profile: see standard geometric representation
  • Extrusion: see standard 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 subtypes).

Figure 283 illustrates a clipping for a straight wall using an IfcPolygonalBoundedHalfSpace as SecondOperand in the IfcBooleanClippingResult.

Figure 284 illustrates a clipping for a curved wall using an IfcHalfSpaceSolid as SecondOperand in the IfcBooleanClippingResult.

straight wall clipping curved wall clipping

Figure 283 — Wall body clipping straight

Figure 284 — Wall body clipping curved

6.1.3.53.2.6 Body SurfaceModel Geometry

Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a single or multiple surface models, based on either shell or face based surface models. It may also include tessellated models.

 

surface model
EXAMPLE  As shown in Figure 149, the surface model representation is given by an IfcShapeRepresentation, which includes a single item which is either an IfcShellBasedSurfaceModel, or an IfcFaceBasedSurfaceModel. In some cases it may also be useful to expose a simple representation as a bounding box representation of the same complex shape.

Figure 149 — Element surface model representation

 

6.1.3.53.2.7 Body SurfaceOrSolidModel Geometry

Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a mixed representation, including surface and solid models.

6.1.3.53.2.8 Body SweptSolid Geometry

The following additional constraints apply to the 'SweptSolid' representation:

The following additional constraints apply to the 'SweptSolid' representation, when an IfcMaterialLayerSetUsage is assigned to the IfcSlab:

  • Solid: IfcExtrudedAreaSolid is required,
  • Profile: IfcArbitraryClosedProfileDef and IfcRectangleProfileDef shall be supported.
  • Extrusion: The profile shall be extruded vertically, i.e., in the direction of the z-axis of the co-ordinate system of the referred spatial structure element. It might be further constraint to be in the direction of the global z-axis in implementers agreements. The extrusion axis shall be perpendicular to the swept profile, i.e. pointing into the direction of the z-axis of the Position of the IfcExtrudedAreaSolid.

The profile of a wall is described in the ground view and extruded vertically. The profile (also identical with the foot print of the wall) is defined by the IfcArbitraryClosedProfileDef (excluding its subtypes). The profile is given with all wall connections already resolved.

Figure 281 illustrates a body representation for a straight wall. In case of a straight wall, the two sides of the profile shall be parallel to the wall axis, that is, the wall has a single unchanged thickness.

Figure 282 illustrates a body representation for a curved wall. In case of a curved wall, the two sides of the profile shall be parallel (with defined offset) to the wall axis, that is, the wall has a single unchanged thickness.

straight wall body curved wall body

Figure 281 — Wall body extrusion straight

Figure 282 — Wall body extrusion curved

6.1.3.53.2.9 Body Tessellation Geometry

Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a single or multiple tessellated surface models, in particular triangulated surface models.

6.1.3.53.2.10 Box Geometry

bounding box
EXAMPLE  Any IfcElement may be represented by a bounding box, which shows the maximum extend of the body within the object coordinate system established by the IfcObjectPlacement. As shown in Figure 148, the bounding box representation is given by an IfcShapeRepresentation that includes a single item, an IfcBoundingBox.

Figure 148 — Building element box representation

 

6.1.3.53.2.11 Classification Association

Any object occurrence or object type can have a reference to a specific classification reference, i.e. to a particular facet within a classification system.

6.1.3.53.2.12 CoG Geometry

The 'CoG', Center of Gravity, shape representation is used as a means to verify the correct import by comparing the CoG of the imported geometry with the explicily provided CoG created during export.

6.1.3.53.2.13 Element Decomposition

An elemented wall is decomposed into parts for particular components such as framing and panels on each side. There must be an object corresponding to each type of part, however there may be single object instance indicating multiple placements (via mapping geometry) for each part, or multiple instances corresponding to each placement. For minimizing file size, it is recommended to use a single object with multiple placement unless there are specific connectivity relationships indicated (e.g. a junction box connected to a specific stud).

RelatedObjects
'IfcElementAssembly'
'IfcBuildingElementPart'

6.1.3.53.2.14 Element Projecting

6.1.3.53.2.15 Element Voiding

As shown in Figure 285, openings within the composite wall are directly assigned to IfcWallElementedCase using IfcRelVoidsElement pointing to IfcOpeningElement and apply to all aggregated parts. If individual parts have cutting and other voiding features, then the decomposed parts have a separate voiding relationship IfcRelVoidsElement pointing to IfcVoidingFeature.

voiding

Figure 285 — Wall elemented voiding

6.1.3.53.2.16 FootPrint Geometry

Identifier Type
'FootPrint' 'GeometricCurveSet'
'FootPrint' 'Annotation2D'

6.1.3.53.2.17 Identity

IfcRoot assigns the globally unique ID. In addition it may provide for a name and a description about the concept.

6.1.3.53.2.18 Mapped Geometry

Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented using the 'MappedRepresentation'. This shall be supported as it allows for reusing the geometry definition of a type at all occurrences of the same type. The results are more compact data sets.

The same constraints, as given for 'SurfaceOrSolidModel', 'SurfaceModel', 'Tessellation', 'Brep', and 'AdvancedBrep' geometric representation, shall apply to the IfcRepresentationMap.

6.1.3.53.2.19 Material Layer Set

The material information of the IfcWall is defined by IfcMaterialLayerSet, or as fallback by IfcMaterial, and it is attached either directly or at the IfcWallType. In this case, the material information does not allow to construct a shape by applying the layer definition to the axis representation, to enable this parametric definition, the IfcMaterialLayerSetUsage has to be used instead.

6.1.3.53.2.20 Material Layer Set Usage

The material of IfcWall can be defined by IfcMaterialLayerSetUsage and attached by IfcRelAssociatesMaterial.RelatingMaterial. It is accessible by the inverse HasAssociations relationship. Multi-layer walls can be represented by refering to several IfcMaterialLayer's within the IfcMaterialLayerSet that is referenced from the IfcMaterialLayerSetUsage.

When assigning an IfcMaterialLayerSetUsage to IfcWall it shall imply that the IfcWallType should have a unique IfcMaterialLayerSet, that is referenced by IfcMaterialLayerSetUsage assigned to all occurrences of this IfcWallType.

Material layer set and usage
EXAMPLE  Figure 277 illustrates assignment of IfcMaterialLayerSetUsage and IfcMaterialLayerSet to the wall type and the wall occurrence.

Figure 277 — Wall Standard Object Typing

 

Figure 278 illustrates material layer usage, where the following conventions shall be met:

  • The reference coordinate system is the local coordinate system established by the ObjectPlacement of the IfcWallStandardCase.
  • The reference axis is the axis defined by the IfcShapeRepresentation with RepresentationType='Axis' as one of the Representation.Representations of the IfcWallStandardCase.
  • The IfcMaterialLayerSetUsage.OffsetFromReferenceLine is given as a distance from this axis.
  • The IfcMaterialLayerSetUsage.OffsetFromReferenceLine is the distance parallel to the reference axis and always within the base (XY) plane of the reference coordinate system. A positve value of IfcMaterialLayerSetUsage.OffsetFromReferenceLine would then point into the positive y-axis of the reference coordinate system.
  • The IfcMaterialLayerSetUsage.DirectionSense defines how the IfcMaterialLayer's are assigned to the reference axis. POSITIVE means in direction to the positive y-axis of the reference coordinate system.
  • The Thickness of each IfcMaterialLayer is provided starting from the OffsetFromReferenceLine and in the direction given by DirectionSense. It is applied without any gap or overlap between two consecutive layers. The TotalThickness of the IfcMaterialLayerSet is the sum of all layer thicknesses.
  • The IfcMaterialLayerSetUsage.LayerSetDirection is always AXIS2.
wall material layer set

Figure 278 — Wall material layers

6.1.3.53.2.21 Object Predefined Type

6.1.3.53.2.22 Object Typing

RelatingType
'IfcWallType'

6.1.3.53.2.23 Object User Identity

An attribute Name and optionally Description can be used for all subypes of IfcObject. For those subtypes, that have an object type definition, such as ifcBeam - IfcBeamType, the common Name and optionally Description is associated with the object type.

6.1.3.53.2.24 Path Connectivity

6.1.3.53.2.25 Product Geometric Representation

The geometric representation of any IfcProduct is provided by the IfcProductDefinitionShape allowing multiple geometric representations. It uses the Product Placement concept utilizing IfcLocalPlacement to establish an object coordinate system, within all geometric representations are founded.

NOTE  A detailed specification of how to apply the local placement and which shape representaions are applicable is provided at the level of subtypes of IfcProduct and is further determined by the model view definition and implementer agreements.

6.1.3.53.2.26 Product Local Placement

The use of local placement is defined at the supertype IfcWall. The local placement of the IfcWallElementedCase defines the parent coordinate systems for the parts within the decomposition. All parts shall be positioned relative to the IfcWallElementedCase.

HasPlacement
'IfcLocalPlacement'
'IfcLocalPlacement'

6.1.3.53.2.27 Product Placement

The Product Placement establishes the object coordinate system and is required, if a geometric shape representation is provided for this product.

6.1.3.53.2.28 Property Sets for Objects

PsetName
'Pset_WallCommon'
'Pset_ConcreteElementGeneral'
'Pset_PrecastConcreteElementFabrication'
'Pset_PrecastConcreteElementGeneral'
'Pset_ReinforcementBarPitchOfWall'
'Pset_EnvironmentalImpactIndicators'
'Pset_EnvironmentalImpactValues'
'Pset_Condition'
'Pset_ManufacturerOccurrence'
'Pset_ManufacturerTypeInformation'
'Pset_ServiceLife'
'Pset_Warranty'

6.1.3.53.2.29 Property Sets with Override

Any object occurrence can hold property sets, either directly at the object occurrence as element specific property sets, or at the object type, as type property sets. In this case, the properties that are provided to the object occurrence are the combinations of element specific and type properties. In case, that the same property (within the same property set, is defined both, in occurrence and type properties, the property value of the occurrence property overrides the property value of the type property.

6.1.3.53.2.30 Quantity Sets

QsetName
'Qto_WallBaseQuantities'

6.1.3.53.2.31 Revision Control

Ownership, history, and merge state is captured using IfcOwnerHistory.

6.1.3.53.2.32 Spatial Containment

The IfcWall, 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.
RelatingStructure
'IfcBuildingStorey'
'IfcBuilding'
'IfcSite'

6.1.3.53.2.33 Surface Geometry

The 'Surface Geometry' shape representation can be used to define a surfacic model of the building (e.g. for analytical purposes, or for reduced Level of Detail representation). It could suppress the geometric details of the parts in the decomposition.

NOTE  It is invalid to exchange a 'Body' shape representation of an IfcWallElementedCase. The body geometry is defined by the parts within the decomposition.

6.1.3.53.3 Formal representations

ENTITY IfcWallElementedCase
 SUBTYPE OF (IfcWall);
 WHERE
	HasDecomposition : HIINDEX(SELF\IfcObjectDefinition.IsDecomposedBy) > 0;
END_ENTITY;