IfcStructuralAnalysisModel

Semantic definitions at the entity

Entity definition

The IfcStructuralAnalysisModel is used to assemble all information needed to represent a structural analysis model. It encompasses certain general properties (such as analysis type), references to all contained structural members, structural supports or connections, as well as loads and the respective load results.

Important functionalities for the description of an analysis model are derived from existing IFC entities:

From IfcSystem it inherits the ability to couple the analysis model via IfcRelServicesBuildings to one or more IfcBuildings as necessary.
From IfcGroup it inherits the inverse attribute IsGroupedBy, pointing to the relationship class IfcRelAssignsToGroup. This allows to group structural members (instances of IfcStructuralMember), and supports (instances of IfcStructuralConnection) which belong to a specific analysis model.
NOTE Loads (as instances of IfcStructuralAction) are not included through IsGroupedBy. Loads are assigned through the LoadedBy attribute relationship, using load groups as a grouping mechanism. Only top-level load groups should be referenced via LoadedBy, i.e. load combinations if any load combinations exist, or load cases if no load combinations exist in this analysis model.

NOTE Results (as instances of IfcStructuralReaction) are not included through IsGroupedBy. Results are assigned through the HasResults attribute relationship, using result groups as a grouping mechanism.
From IfcObject it inherits the inverse attribute IsDecomposedBy pointing to the relationship class IfcRelNests. It provides the hierarchy between the separate (partial) analysis models.

HISTORY New entity in IFC2x2.

IFC4 CHANGE Attribute SharedPlacement and informal propositions added, allowing for easy retrieval of the common object placement and for specification of the analysis model's coordiante system before any structural item is instantiated. WHERE rule added.

Informal Propositions:

If one or more structural item (instance of a subtype of IfcStructuralItem) is grouped into an IfcStructuralAnalysisModel, the attribute SharedPlacement shall be provided with a value.
The ObjectPlacements of all structural items which are grouped into the same instance of IfcStructuralAnalysisModel shall refer to the same instance of IfcObjectPlacement as IfcStructuralAnalysisModel.SharedPlacement.

NOTE This rule is necessary to achieve consistent topology representations. The topology representations of structural items in an analysis model are meant to share vertices and edges und must therefore have the same object placement.

NOTE A structural item may be grouped into more than one analysis model. In this case, all these models must use the same instance of IfcObjectPlacement.

Attribute definitions

#	Attribute	Type	Cardinality	Description	C
6	PredefinedType	IfcAnalysisModelTypeEnum	[1:1]	Defines the type of the structural analysis model.	X
7	OrientationOf2DPlane	IfcAxis2Placement3D	[0:1]	If the selected model type (PredefinedType) describes a 2D system, the orientation defines the analysis plane (P[1], P[2]) and the normal to the analysis plane (P[3]). This is needed because structural items and activities are always defined in three-dimensional space even if they are meant to be analysed in a two-dimensional manner. In case of predefined type IN_PLANE_LOADING_2D, the analysis is to be performed within the projection into the P[1], P[2] plane. In case of predefined type OUT_PLANE_LOADING_2D, only the P[3] component of loads and their effects is meant to be analyzed. This is used for beam grids and for typical slab analyses. In case of predefined type LOADING_3D, OrientationOf2DPlane shall be omitted.	X
8	LoadedBy	IfcStructuralLoadGroup	S[1:?]	References to all load groups to be analyzed.	X
9	HasResults	IfcStructuralResultGroup	S[1:?]	References to all result groups available for this structural analysis model.	X
10	SharedPlacement	IfcObjectPlacement	[0:1]	Object placement which shall be common to all items and activities which are grouped into this instance of IfcStructuralAnalysisModel. This placement establishes a coordinate system which is referred to as 'global coordinate system' in use definitions of various classes of structural items and activities. NOTE Most commonly, but not necessarily, the SharedPlacement is an IfcLocalPlacement whose z axis is parallel with the z axis of the IfcProject's world coordinate system and directed like the WCS z axis (i.e. pointing "upwards") or directed against the WCS z axis (i.e. points "downwards"). NOTE Per informal proposition, this attribute is not optional as soon as at least one IfcStructuralItem is grouped into the instance of IfcStructuralAnalysisModel.	X

Formal Propositions

Rule	Description
HasObjectType	The attribute ObjectType shall be given if the predefined type is set to USERDEFINED.

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	C
IfcRoot
1	GlobalId	IfcGloballyUniqueId	[1:1]	Assignment of a globally unique identifier within the entire software world.	X
2	OwnerHistory	IfcOwnerHistory	[0:1]	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.	X
3	Name	IfcLabel	[0:1]	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
4	Description	IfcText	[0:1]	Optional description, provided for exchanging informative comments.	X
IfcObjectDefinition
	HasAssignments	IfcRelAssigns @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
	Nests	IfcRelNests @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).	X
	IsNestedBy	IfcRelNests @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).	X
	HasContext	IfcRelDeclares @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.	X
	IsDecomposedBy	IfcRelAggregates @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).	X
	Decomposes	IfcRelAggregates @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).	X
	HasAssociations	IfcRelAssociates @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
5	ObjectType	IfcLabel	[0:1]	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
	IsDeclaredBy	IfcRelDefinesByObject @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.	X
	Declares	IfcRelDefinesByObject @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.	X
	IsTypedBy	IfcRelDefinesByType @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.	X
	IsDefinedBy	IfcRelDefinesByProperties @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.	X
IfcGroup
	IsGroupedBy	IfcRelAssignsToGroup @RelatingGroup	S[0:?]	Reference to the relationship IfcRelAssignsToGroup that assigns the one to many group members to the IfcGroup object.	X
IfcSystem
	ServicesBuildings	IfcRelServicesBuildings @RelatingSystem	S[0:1]	Reference to the ~~building~~ spatial structure via the objectified relationship IfcRelServicesBuildings, which is serviced by the system.	X
IfcStructuralAnalysisModel
6	PredefinedType	IfcAnalysisModelTypeEnum	[1:1]	Defines the type of the structural analysis model.	X
7	OrientationOf2DPlane	IfcAxis2Placement3D	[0:1]	If the selected model type (PredefinedType) describes a 2D system, the orientation defines the analysis plane (P[1], P[2]) and the normal to the analysis plane (P[3]). This is needed because structural items and activities are always defined in three-dimensional space even if they are meant to be analysed in a two-dimensional manner. In case of predefined type IN_PLANE_LOADING_2D, the analysis is to be performed within the projection into the P[1], P[2] plane. In case of predefined type OUT_PLANE_LOADING_2D, only the P[3] component of loads and their effects is meant to be analyzed. This is used for beam grids and for typical slab analyses. In case of predefined type LOADING_3D, OrientationOf2DPlane shall be omitted.	X
8	LoadedBy	IfcStructuralLoadGroup	S[1:?]	References to all load groups to be analyzed.	X
9	HasResults	IfcStructuralResultGroup	S[1:?]	References to all result groups available for this structural analysis model.	X
10	SharedPlacement	IfcObjectPlacement	[0:1]	Object placement which shall be common to all items and activities which are grouped into this instance of IfcStructuralAnalysisModel. This placement establishes a coordinate system which is referred to as 'global coordinate system' in use definitions of various classes of structural items and activities. NOTE Most commonly, but not necessarily, the SharedPlacement is an IfcLocalPlacement whose z axis is parallel with the z axis of the IfcProject's world coordinate system and directed like the WCS z axis (i.e. pointing "upwards") or directed against the WCS z axis (i.e. points "downwards"). NOTE Per informal proposition, this attribute is not optional as soon as at least one IfcStructuralItem is grouped into the instance of IfcStructuralAnalysisModel.	X

Definitions applying to Common Use Definitions

Instance diagram

Concept usage

Aggregation

The Aggregation concept applies to this entity as shown in Table 624.

PredefinedType	RelatedObjects	Description
	IfcStructuralAnalysisModel	This relationship provides the hierarchy between separate (partial) analysis models.

Table 624 — IfcStructuralAnalysisModel Aggregation

Group Assignment

The Group Assignment concept applies to this entity as shown in Table 625.

RelatedType	Description
	Structural members and connections assigned to the analysis model.

Table 625 — IfcStructuralAnalysisModel Group Assignment

Concept inheritance

#	Concept	Model View
IfcRoot
	Software Identity	Common Use Definitions
	Revision Control	Common Use Definitions
IfcObject
	Object Occurrence Predefined Type	Common Use Definitions
IfcGroup
IfcSystem
	Property Sets for Objects	Common Use Definitions
IfcStructuralAnalysisModel
	Aggregation	Common Use Definitions
	Group Assignment	Common Use Definitions

Examples

Structural curve member

Formal representations

XSD Specification

 <xs:element name="IfcStructuralAnalysisModel" type="ifc:IfcStructuralAnalysisModel" substitutionGroup="ifc:IfcSystem" nillable="true"/>

 <xs:complexType name="IfcStructuralAnalysisModel">

  <xs:complexContent>

   <xs:extension base="ifc:IfcSystem">

    <xs:sequence>

     <xs:element name="OrientationOf2DPlane" type="ifc:IfcAxis2Placement3D" nillable="true" minOccurs="0"/>

     <xs:element name="LoadedBy" nillable="true" minOccurs="0">

      <xs:complexType>

       <xs:sequence>

        <xs:element ref="ifc:IfcStructuralLoadGroup" maxOccurs="unbounded"/>

       </xs:sequence>

       <xs:attribute ref="ifc:itemType" fixed="ifc:IfcStructuralLoadGroup"/>

       <xs:attribute ref="ifc:cType" fixed="set"/>

       <xs:attribute ref="ifc:arraySize" use="optional"/>

      </xs:complexType>

     </xs:element>

     <xs:element name="HasResults" nillable="true" minOccurs="0">

      <xs:complexType>

       <xs:sequence>

        <xs:element ref="ifc:IfcStructuralResultGroup" maxOccurs="unbounded"/>

       </xs:sequence>

       <xs:attribute ref="ifc:itemType" fixed="ifc:IfcStructuralResultGroup"/>

       <xs:attribute ref="ifc:cType" fixed="set"/>

       <xs:attribute ref="ifc:arraySize" use="optional"/>

      </xs:complexType>

     </xs:element>

     <xs:element name="SharedPlacement" type="ifc:IfcObjectPlacement" nillable="true" minOccurs="0"/>

    </xs:sequence>

    <xs:attribute name="PredefinedType" type="ifc:IfcAnalysisModelTypeEnum" use="optional"/>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcStructuralAnalysisModel

 SUBTYPE OF (IfcSystem);

  PredefinedType : IfcAnalysisModelTypeEnum;

  OrientationOf2DPlane : OPTIONAL IfcAxis2Placement3D;

  LoadedBy : OPTIONAL SET [1:?] OF IfcStructuralLoadGroup;

  HasResults : OPTIONAL SET [1:?] OF IfcStructuralResultGroup;

  SharedPlacement : OPTIONAL IfcObjectPlacement;

 WHERE

  HasObjectType : (PredefinedType <> IfcAnalysisModelTypeEnum.USERDEFINED) OR EXISTS(SELF\IfcObject.ObjectType);
END_ENTITY;

 EXPRESS-G diagram

Link to this page

Item	Change	Description
IFC2x3 to IFC4
IfcStructuralAnalysisModel
OwnerHistory	MODIFIED	Instantiation changed to OPTIONAL.
SharedPlacement	ADDED

	Statisches Modell: Idealisierung zur Berechnung der Auflagerreaktionen und des Kräfteverlaufs
	Structural Analysis Model
	Modèle d'analyse structurelle