IFC 4.3.x development

7.11.3.6 IfcStructuralAnalysisModel

Change log

IFC4

additionsattributes SharedPlacement
additionswhere_rulesHasObjectType

IFC4X3_RC3

additionswhere_rulesCorrectPredefinedType

7.11.3.6.1 Semantic definitions at the entity

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:

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 IfcObjectDefinition it inherits the inverse attribute IsDecomposedBy pointing to the relationship class IfcRelAggregates. 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:

  1. 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.
  2. The ObjectPlacement 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.

7.11.3.6.1 Attributes

# 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.
IfcGroup
IsGroupedBy SET [0:?] OF IfcRelAssignsToGroup FOR RelatingGroup Reference to the relationship IfcRelAssignsToGroup that assigns the one to many group members to the IfcGroup object.

> IFC4 CHANGE  The cardinality has been changed from 1..1 to 0..? in order to allow the exchange of a group concept without having already group members assigned. It now also allows the use of many instances of IfcRelAssignsToGroup to assign the group members. The change has been done with upward compatibility for file based exchange.
IfcSystem
ServicesBuildings SET [0:1] OF IfcRelServicesBuildings FOR RelatingSystem Reference to the ~~building~~ spatial structure via the objectified relationship IfcRelServicesBuildings, which is serviced by the system.
ServicesFacilities SET [0:?] OF IfcRelReferencedInSpatialStructure FOR RelatedElements
IfcStructuralAnalysisModel
6 PredefinedType IfcAnalysisModelTypeEnum
7 OrientationOf2DPlaneOPTIONAL IfcAxis2Placement3D
8 LoadedBy OPTIONAL SET [1:?] OF IfcStructuralLoadGroup
9 HasResults OPTIONAL SET [1:?] OF IfcStructuralResultGroup
10 SharedPlacement OPTIONAL IfcObjectPlacement

7.11.3.6.2 Entity inheritance

dot_inheritance IfcStructuralAnalysisModel IfcStructuralAnalysisModel IfcSystem IfcSystem IfcStructuralAnalysisModel->IfcSystem IfcSystem_children 4 more... IfcSystem_children->IfcSystem IfcGroup IfcGroup IfcSystem->IfcGroup IfcGroup_children 4 more... IfcGroup_children->IfcGroup IfcObject IfcObject IfcGroup->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

7.11.3.6.3 Definitions applying to General Usage

7.11.3.6.3.1 Aggregation

7.11.3.6.3.2 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.

7.11.3.6.3.3 Group Assignment

7.11.3.6.3.4 Identity

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

7.11.3.6.3.5 Object Predefined Type

7.11.3.6.3.6 Object Typing

Any object occurrence can be typed by being assigned to a common object type utilizing this concept. A particular rule, restricting the applicable subtypes of IfcTypeObject that can be assigned, is introduced by overriding this concept at the level of subtypes of IfcObject.

7.11.3.6.3.7 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.

7.11.3.6.3.8 Property Sets

PsetName
'Pset_ServiceLifeFactors'

7.11.3.6.3.9 Property Sets for Objects

Any object occurrence can hold property sets, each being a set of individual properties having name, description, value(s) and unit(s). A reference to applicable property sets, being part of this specification, is introduced at the level of sub types of IfcObject.

7.11.3.6.3.10 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.

7.11.3.6.3.11 Revision Control

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

7.11.3.6.4 Formal representations

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);
	CorrectPredefinedType : NOT(EXISTS(PredefinedType)) OR
(PredefinedType <> IfcAnalysisModelTypeEnum.USERDEFINED) OR
((PredefinedType = IfcAnalysisModelTypeEnum.USERDEFINED) AND EXISTS(SELF\IfcObject.ObjectType));
END_ENTITY;