#### 5.4.3.14 IfcSpatialStructureElement

| Elément de la structure spatiale
| Räumliches Strukturelement

A spatial structure element (IfcSpatialStructureElement) is the generalization of all spatial elements that might be used to define a spatial structure. That spatial structure is often used to provide a project structure to organize a building project.

A spatial project structure might define as many levels of decomposition as necessary for the building project. Elements within the spatial project structure are:

- site as IfcSite
- building as IfcBuilding
- storey as IfcBuildingStorey
- space as IfcSpace

or aggregations or parts thereof. The composition type declares an element to be either an element itself, or an aggregation (complex) or a decomposition (part). The interpretation of these types is given at each subtype of IfcSpatialStructureElement.

The IfcRelAggregates is defined as an 1-to-many relationship and used to establish the relationship between exactly two levels within the spatial project structure. Finally the highest level of the spatial structure is assigned to IfcProject using the IfcRelAggregates.

Informal Propositions:

1. The spatial project structure, established by the IfcRelAggregates, shall be acyclic.
2. A site should not be (directly or indirectly) associated to a building, storey or space.
3. A building should not be (directly or indirectly) associated to a storey or space.
4. A storey should not be (directly or indirectly) associated to a space.

> HISTORY New entity in IFC2x.

Relationship Use Definition

The subtypes of IfcSpatialStructureElement relate to other elements and systems by establishing the following relationships:

- Containment of elements : IfcRelContainedInSpatialStructure by inverse attribute ContainsElements, used to assign any element, like building elements, MEP elements, etc. to the spatial structure element in which they are primarily contained.
  - NOTE This relationship is mandatory for elements in several view definitions and implementer agreements.
- Reference of elements : IfcRelReferencedInSpatialStructure by inverse attribute ReferencesElements, used to reference any element, like building elements, MEP elements, etc. in spatial structure elements, other then the one, where it is contained.
- Reference of systems : IfcRelServicesBuildings by inverse attribute ServicedBySystems, used to reference a sytem, like a building service or electrical distribution system, a zonal system, or a structural analysis system, that is assigned to this spatial structure element.
  - NOTE Elements within the referenced system may be directly contained (or referenced) by other spatial structure elements.

The subtypes of IfcSpatialStructureElement relate to each other by using the IfcRelAggregates relationship to build the project spatial structure.

Figure 54 shows the use of IfcRelAggregates to establish a spatial structure including site, building, building section and storey. More information is provided at the level of the subtypes.

Figure 54 — Spatial structure element composition

XSD Specification:

<xs:element name="IfcSpatialStructureElement" type="ifc:IfcSpatialStructureElement" abstract="true" substitutionGroup="ifc:IfcSpatialElement" nillable="true"/>
<xs:complexType name="IfcSpatialStructureElement" abstract="true">
<xs:complexContent>
<xs:extension base="ifc:IfcSpatialElement"/>
</xs:complexContent>
</xs:complexType>

EXPRESS Specification:

ENTITY IfcSpatialStructureElement

| ABSTRACT SUPERTYPE OF(ONEOF(IfcBuilding, IfcBuildingStorey, IfcSite, IfcSpace))

| SUBTYPE OF IfcSpatialElement;

CompositionType | : | OPTIONAL IfcStrippedOptional;

| WHERE

WR41 | : | (HIINDEX(SELF\IfcObjectDefinition.Decomposes) = 1) AND ('IFCKERNEL.IFCRELAGGREGATES' IN TYPEOF(SELF\IfcObjectDefinition.Decomposes[1])) AND (('IFCKERNEL.IFCPROJECT' IN TYPEOF (SELF\IfcObjectDefinition.Decomposes[1].RelatingObject)) OR ('IFCPRODUCTEXTENSION.IFCSPATIALSTRUCTUREELEMENT' IN TYPEOF (SELF\IfcObjectDefinition.Decomposes[1].RelatingObject)) );

END_ENTITY;

EXPRESS-G diagram

Attribute Definitions:

Formal Propositions:

WR41 | : | All spatial structure elements shall be associated (using the IfcRelAggregates relationship) with another spatial structure element, or with IfcProject.

Inheritance Graph:

ENTITY IfcSpatialStructureElement

| ENTITY IfcRoot

GlobalId | : | IfcGloballyUniqueId;
OwnerHistory | : | OPTIONAL IfcOwnerHistory;
Name | : | OPTIONAL IfcLabel;
Description | : | OPTIONAL IfcText;

| ENTITY IfcObjectDefinition

| INVERSE

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;

| INVERSE

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 IfcStrippedOptional;

| INVERSE

ReferencedBy | : | SET OF IfcRelAssignsToProduct FOR RelatingProduct;

| ENTITY IfcSpatialElement

LongName | : | OPTIONAL IfcLabel;

| INVERSE

ContainsElements | : | SET OF IfcRelContainedInSpatialStructure FOR RelatingStructure;

| ENTITY IfcSpatialStructureElement

CompositionType | : | OPTIONAL IfcStrippedOptional;

END_ENTITY;

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