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	B
6	PredefinedType	IfcAnalysisModelTypeEnum	[1:1]	Defines the type of the structural analysis model.	X
7	OrientationOf2DPlane	-		This attribute is out of scope for this model view definition and shall not be set.
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	-		This attribute is out of scope for this model view definition and shall not be set.

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	B
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).
	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.
	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	-		This attribute is out of scope for this model view definition and shall not be set.
	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
IfcStructuralAnalysisModel
6	PredefinedType	IfcAnalysisModelTypeEnum	[1:1]	Defines the type of the structural analysis model.	X
7	OrientationOf2DPlane	-		This attribute is out of scope for this model view definition and shall not be set.
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	-		This attribute is out of scope for this model view definition and shall not be set.

Definitions applying to Bridge View

Instance diagram

Structural analysis of bridges involves analytical models that approximate the physical behavior of specific bridge geometry. Such analytical models may make use of curve members, surface members, and volumetric members. Finite element analysis may be applied, effectively reducing everything into a mesh of nodes and linear members. Within such structural model, load cases and combinations may be defined, with resulting stresses and displacements captured.

For the purposes of design plans, inclusion of full structural analysis information may not be necessary, however the resulting stresses and deflections at each member according to each load combination must be captured, to determine allowable loading during construction.

The specific plans for this example contain resulting shear and moments at locations along girder spans, and displacements from dead loads used to calculate camber ordinates. Additionally, the plans indicate the load cases and combinations.

Figure 65 — Bridge structural reactions

Concept usage

Group Assignment

The Group Assignment concept applies to this entity as shown in Table 80.

RelatedType	Description
IfcStructuralPointConnection	Structural connections which may correspond to ground supports, bearings, and field splices
IfcStructuralCurveMember	Structural members with constant profile
IfcStructuralCurveMemberVarying	Structural members with varying profile
IfcStructuralCurveConnection	Structural connections between members
IfcStructuralSurfaceMember	Structural surface members with constant thickness
IfcStructuralSurfaceMemberVarying	Structural surface members with varying thickness
IfcStructuralSurfaceConnection	Structural connections between surfaces

Table 80 — IfcStructuralAnalysisModel Group Assignment

Exchange
Import		O	R
Export		O	R

Structural Analysis Model Attributes

The Structural Analysis Model Attributes concept applies to this entity.

Exchange
Import		O	R
Export		O	R

Concept inheritance

#	Concept	Model View
IfcRoot
	Software Identity	Bridge View
	User Identity	Bridge View
	Object Ownership	Bridge View
IfcObject
	Property Sets for Objects	Bridge View
IfcStructuralAnalysisModel
	Group Assignment	Bridge View
	Structural Analysis Model Attributes	Bridge View

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="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: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 IfcStrippedOptional;

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

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

  SharedPlacement : OPTIONAL IfcStrippedOptional;

 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