7.10.3.8 IfcStructuralCurveAction

7.10.3.8.1 Semantic definition

A structural curve action defines an action which is distributed over a curve. A curve action may be connected with a curve member or curve connection, or surface member or surface connection.

*Coordinate Systems*:

See definitions at IfcStructuralActivity.

*Topology Use Definitions*:

Standard Case: If connected with a curve item, instances of IfcStructuralCurveAction shall not have an ObjectPlacement nor a Representation. It is implied that the placement and representation of the IfcStructuralActivity is the same as the ones of the member or connection.

Special Case 1: If connected with a surface item, instances of IfcStructuralCurveAction shall have an ObjectPlacement and Representation, containing an IfcEdgeCurve. See IfcStructuralActivity for further definitions.

Special Case 2: If not connected with a structural item (which may happen in an incomplete or conceptual model), a curve action should have an ObjectPlacement and Representation, containing an IfcEdgeCurve. See IfcStructuralActivity for further definitions.

Informal Propositions

If the curve action is of the predefined type CONST, SINUS, or PARABOLA, SELF\IfcStructuralActivity.AppliedLoad must not be of type IfcStructuralLoadConfiguration. In case of SINUS and PARABOLA, the load item defines the maximum of the load at the centre of the load distribution.
If the curve action is of the predefined type LINEAR, SELF\IfcStructuralActivity.AppliedLoad shall be of type IfcStructuralLoadConfiguration and shall contain two items.
If the curve action is of the predefined type POLYGONAL, SELF\IfcStructuralActivity.AppliedLoad shall be of type IfcStructuralLoadConfiguration and shall contain three or more items.
If the curve action is of the predefined type DISCRETE, SELF\IfcStructuralActivity.AppliedLoad shall be of type IfcStructuralLoadConfiguration and shall contain two or more items.
In case of types LINEAR, POLYGONAL, and DISCRETE, the load items shall have one-dimensional IfcStructuralLoadConfiguration.Locations, defining the location of the load samples in local coordinates of the curve action. The load items shall be provided in ascending order according to their locations. The first and the last load item define the extent of the load distribution.
Point actions must be of type DISCRETE, thus contain two or more load points. (Single point loads are modeled by IfcStructuralPointAction.)
All items in SELF\IfcStructuralActivity.AppliedLoad\IfcStructuralLoadConfiguration.Values shall be of the same entity type.

7.10.3.8.2 Entity inheritance

7.10.3.8.3 Attributes

#	Attribute	Type	Description
IfcRoot (4)
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 is 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 (7)
	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 structures 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 definition 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 definition can only be part of a single decomposition (to allow hierarchical structures 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)
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 or when the concrete entity instantiated does not have a PredefinedType attribute. The latter is the case in some exceptional leaf classes and when instantiating IfcBuiltElement directly.
	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 was previously 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 (5)
6	ObjectPlacement	OPTIONAL IfcObjectPlacement	This establishes the object coordinate system and 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 constrained (e.g. relative to grid axes, or to a linear positioning element). The type of placement is determined by the various subtypes of IfcObjectPlacement. An object placement must be provided if a representation is present.
7	Representation	OPTIONAL IfcProductRepresentation	Reference to the representations of the product, being either a representation (IfcProductRepresentation) or as a special case of a shape representation (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:?] OF IfcRelPositions FOR RelatedProducts	Reference to the IfcRelPositions relationship, which defines its relationship with a positioning element.
	ReferencedInStructures	SET [0:?] OF IfcRelReferencedInSpatialStructure FOR RelatedElements	Reference to the objectified relationship IfcRelReferencedInSpatialStructure may be used to relate a product to one or more spatial structure elements in addition to the one in which it is primarily contained.
IfcStructuralActivity (3)
8	AppliedLoad	IfcStructuralLoad	Load or result resource object which defines the load type, direction, and load values. In case of activities which are variably distributed over curves or surfaces, IfcStructuralLoadConfiguration is used which provides a list of load samples and their locations within the load distribution, measured in local coordinates of the curve or surface on which this activity acts. The contents of this load or result distribution may be further restricted by definitions at subtypes of IfcStructuralActivity.
9	GlobalOrLocal	IfcGlobalOrLocalEnum	Indicates whether the load directions refer to the global coordinate system (global to the analysis model, i.e. as established by IfcStructuralAnalysisModel.SharedPlacement) or to the local coordinate system (local to the activity or connected item, as established by an explicit or implied representation and its parameter space). NOTE , the informal definition of IfcRepresentationResource.IfcGlobalOrLocalEnum doe s not distinguish between "global coordinate system" and "world coordinate system". On the other hand, this distinction is necessary in the IfcStructuralAnalysisDomain where the shared "global" coordinate system of an analysis model may very well not be the same as the project-wide world coordinate system. NOTE In the scope of IfcStructuralActivity.GlobalOrLocal, the meaning of GLOBAL_COORDS is therefore not to be taken as world coordinate system but as the analysis model specific shared coordinate system. In contrast, LOCAL_COORDS is to be taken as coordinates which are local to individual structural items and activities, as established by subclass-specific geometry use definitions.
	AssignedToStructuralItem	SET [0:1] OF IfcRelConnectsStructuralActivity FOR RelatedStructuralActivity	Reference to the IfcRelConnectsStructuralActivity relationship by which activities are connected with structural items.
IfcStructuralAction (1)
10	DestabilizingLoad	OPTIONAL IfcBoolean	Indicates if this action may cause a stability problem. If it is 'FALSE', no further investigations regarding stability problems are necessary.
Click to show 25 hidden inherited attributes
IfcStructuralCurveAction (2)
11	ProjectedOrTrue	OPTIONAL IfcProjectedOrTrueLengthEnum	Defines whether load values are given per true length of the curve on which they act, or per length of the projection of the curve in load direction. The latter is only applicable to loads which act in global coordinate directions.
12	PredefinedType	IfcStructuralCurveActivityTypeEnum	Type of action according to its distribution of load values.

Table 7.10.3.8.B

7.10.3.8.4 Formal propositions

Name Description

HasObjectType

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

(PredefinedType <> IfcStructuralCurveActivityTypeEnum.USERDEFINED) OR EXISTS(SELF\IfcObject.ObjectType)

ProjectedIsGlobal

A load can only be related to projected length if it was specified in global coordinate directions (i.e. in analysis model coordinate directions). If a load was specified in local coordinate directions, it can only relate to true length.

 (NOT EXISTS(ProjectedOrTrue)) OR
((ProjectedOrTrue <> PROJECTED_LENGTH) OR
 (SELF\IfcStructuralActivity.GlobalOrLocal = GLOBAL_COORDS))

SuitablePredefinedType

The EQUIDISTANT distribution type is out of scope of structural curve actions.

PredefinedType <> IfcStructuralCurveActivityTypeEnum.EQUIDISTANT

Table 7.10.3.8.C

7.10.3.8.5 Property sets

Pset_Risk
- RiskName
- RiskType
- NatureOfRisk
- RiskAssessmentMethodology
- UnmitigatedRiskLikelihood
- UnmitigatedRiskConsequence
- UnmitigatedRiskSignificance
- MitigationPlanned
- MitigatedRiskLikelihood
- MitigatedRiskConsequence
- MitigatedRiskSignificance
- MitigationProposed
- AssociatedProduct
- AssociatedActivity
- AssociatedLocation
Pset_Tolerance
- ToleranceDescription
- ToleranceBasis
- OverallTolerance
- HorizontalTolerance
- OrthogonalTolerance
- VerticalTolerance
- PlanarFlatness
- HorizontalFlatness
- ElevationalFlatness
- SideFlatness
- OverallOrthogonality
- HorizontalOrthogonality
- OrthogonalOrthogonality
- VerticalOrthogonality
- OverallStraightness
- HorizontalStraightness
- OrthogonalStraightness
- VerticalStraightness
Pset_Uncertainty
- UncertaintyBasis
- UncertaintyDescription
- HorizontalUncertainty
- LinearUncertainty
- OrthogonalUncertainty
- VerticalUncertainty
Qto_BodyGeometryValidation
- GrossSurfaceArea
- NetSurfaceArea
- GrossVolume
- NetVolume
- SurfaceGenusBeforeFeatures
- SurfaceGenusAfterFeatures

7.10.3.8.6 Concept usage

Concept	Usage	Description
IfcRoot (2)
Revision Control	General	Ownership, history, and merge state is captured using IfcOwnerHistory.
Software Identity	General	IfcRoot assigns the globally unique ID. In addition it may provide for a name and a description about the concept.
IfcObjectDefinition (9)
Classification Association	General	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.
Aggregation	General	No description available.
Approval Association	General	No description available.
Constraint Association	General	No description available.
Document Association	General	No description available.
Library Association	General	No description available.
Material Association	General	No description available.
Material Single	General	No description available.
Nesting	General	No description available.
IfcObject (5)
Object Predefined Type	General	No description available.
Object Typing	General	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. This concept can be applied to the following resources: IfcTypeObject
Object User Identity	General	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.
Property Sets with Override	General	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.
Assignment to Group	General	No description available.
IfcProduct (18)
Body Geometry	General	The body or solid model geometric representation of an IfcProduct is typically defined using a Tessellation or Brep. Subtypes may provide recommendations on other representation types that may be used. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used: IfcShapeRepresentation.RepresentationIdentifier = 'Body' IfcShapeRepresentation.RepresentationType = Typically 'Tessellation' or 'Brep'
Product Geometric Representation	General	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, in which all geometric representations are founded. NOTE A detailed specification of how to apply the local placement and which shape representations are applicable is provided at the level of subtypes of IfcProduct and is further determined by the model view definition and implementer agreements.
Product Geometry Colour	General	No description available.
Product Geometry Layer	General	No description available.
Product Relative Positioning	General	If the IfcProduct Product Placement is placed relative to an IfcPositioningElement this relationship covers the information on which IfcPositioningElement positions the IfcProduct.
Product Span Positioning	General	No description available.
Box Geometry	General	No description available.
CoG Geometry	General	No description available.
Mapped Geometry	General	No description available.
Object Typing	General	This is a further elaboration on an inherited concept. This concept can be applied to the following resources: IfcTypeProduct
Product Local Placement	General	No description available.
Product Topology Representation	General	No description available.
Property Sets for Objects	General	This concept can be applied to the following resources: Pset_Risk Pset_Tolerance Pset_Uncertainty
Quantity Sets	General	This concept can be applied to the following resources: Qto_BodyGeometryValidation
Reference Geometry	General	No description available.
Reference SweptSolid Geometry	General	No description available.
Reference SweptSolid PolyCurve Geometry	General	No description available.
Reference Tessellation Geometry	General	No description available.
Click to show 34 hidden inherited concepts

Table 7.10.3.8.D

7.10.3.8.7 Examples

Figure 7.10.3.8.A

Structural Curve Member

7.10.3.8.8 Formal representation

 ENTITY IfcStructuralCurveAction
 SUPERTYPE OF (ONEOF
	(IfcStructuralLinearAction))
 SUBTYPE OF (IfcStructuralAction);
	ProjectedOrTrue : OPTIONAL IfcProjectedOrTrueLengthEnum;
	PredefinedType : IfcStructuralCurveActivityTypeEnum;
 WHERE
	HasObjectType : (PredefinedType <> IfcStructuralCurveActivityTypeEnum.USERDEFINED) OR EXISTS(SELF\IfcObject.ObjectType);
	ProjectedIsGlobal : (NOT EXISTS(ProjectedOrTrue)) OR
((ProjectedOrTrue <> PROJECTED_LENGTH) OR
 (SELF\IfcStructuralActivity.GlobalOrLocal = GLOBAL_COORDS));
	SuitablePredefinedType : PredefinedType <> IfcStructuralCurveActivityTypeEnum.EQUIDISTANT;
END_ENTITY;