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 | Structural Curve Member |
| Item | SPF | XML | Change | Description | IFC2x3 to IFC4 4.0.0.0 |
|---|---|---|---|---|
| IfcStructuralCurveMember | ||||
| OwnerHistory | MODIFIED | Instantiation changed to OPTIONAL. | ||
| PredefinedType | MODIFIED | Type changed from IfcStructuralCurveTypeEnum to IfcStructuralCurveMemberTypeEnum. | ||
| Axis | ADDED | IFC4x2 Candidate 4.2.0.0 | ||
| IfcStructuralCurveMember | ||||
| PositionedRelativeTo | ADDED | IFC4x2 to IFC4x3_RC1 | ||
| IfcStructuralCurveMember | ||||
| ReferencedInStructures | ADDED |
Instances of IfcStructuralCurveMember describe edge members, i.e. structural analysis idealizations of beams, columns, rods etc.. Curve members may be straight or curved.
HISTORY New entity in IFC2x2.
IFC4 CHANGE Attribute Axis and WHERE rule added. Use definitions changed.
Coordinate Systems:
See definitions at IfcStructuralItem. The local coordinate system is established by the reference curve given by topology representation and by the attribute Axis. The local x axis is parallel with the tangent on the reference curve. The local z axis is located in the surface which is created by sweeping Axis along the reference curve and is directed according to Axis. The local y axis is directed such that x,y,z form a right-handed Cartesian coordinate system.
| # | Attribute | Type | Cardinality | Description | G |
|---|---|---|---|---|---|
| 8 | PredefinedType | IfcStructuralCurveMemberTypeEnum | Type of member with respect to its load carrying behavior in this analysis idealization. | X | |
| 9 | Axis | IfcDirection |
Direction which is used in the definition of the local z axis. Axis is specified relative to the so-called global coordinate system, i.e. the SELF\IfcProduct.ObjectPlacement.
NOTE It is desirable and usually possible that many instances of IfcStructuralCurveConnection and IfcStructuralCurveMember share a common instance of IfcDirection as their Axis attribute. | X |
| Rule | Description |
|---|---|
| HasObjectType | The attribute ObjectType shall be given if the predefined type is set to USERDEFINED. |
| # | Attribute | Type | Cardinality | Description | G |
|---|---|---|---|---|---|
| IfcRoot | |||||
| 1 | GlobalId | IfcGloballyUniqueId | Assignment of a globally unique identifier within the entire software world. | X | |
| 2 | OwnerHistory | 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. | X |
| 3 | Name | 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. | X |
| 4 | Description | IfcText | ? | 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).
IFC4 CHANGE The inverse attribute datatype has been added and separated from Decomposes defined at IfcObjectDefinition. | 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).
IFC4 CHANGE The inverse attribute datatype has been added and separated from IsDecomposedBy defined at IfcObjectDefinition. | 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.
IFC4 CHANGE The inverse attribute datatype has been added. | 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).
IFC4 CHANGE The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates. | 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).
IFC4 CHANGE The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates. | 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 | ? | 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.
IFC4 CHANGE New inverse relationship, change made with upward compatibility for file based exchange. | 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.
IFC4 CHANGE New inverse relationship, change made with upward compatibility for file based exchange. | 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.
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. | 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.
IFC4 CHANGE The data type has been changed from IfcRelDefines to IfcRelDefinesByProperties with upward compatibility for file based exchange. | X | |
| IfcProduct | |||||
| 6 | ObjectPlacement | IfcObjectPlacement | ? | 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 constraint (e.g. relative to grid axes). It is determined by the various subtypes of IfcObjectPlacement, which includes the axis placement information to determine the transformation for the object coordinate system. | X |
| 7 | Representation | IfcProductRepresentation | ? | Reference to the representations of the product, being either a representation (IfcProductRepresentation) or as a special case a shape representations (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. | X |
| ReferencedBy | IfcRelAssignsToProduct @RelatingProduct | S[0:?] | Reference to the IfcRelAssignsToProduct relationship, by which other products, processes, controls, resources or actors (as subtypes of IfcObjectDefinition) can be related to this product. | X | |
| PositionedRelativeTo | IfcRelPositions @RelatedProducts | S[0:?] | X | ||
| ReferencedInStructures | IfcRelReferencedInSpatialStructure @RelatedElements | S[0:?] | X | ||
| IfcStructuralItem | |||||
| AssignedStructuralActivity | IfcRelConnectsStructuralActivity @RelatingElement | S[0:?] | Inverse relationship to all structural activities (i.e. to actions or reactions) which are assigned to this structural member. | X | |
| IfcStructuralMember | |||||
| ConnectedBy | IfcRelConnectsStructuralMember @RelatingStructuralMember | S[0:?] | Inverse relationship to all structural connections (i.e. to supports or connecting elements) which are defined for this structural member. | X | |
| IfcStructuralCurveMember | |||||
| 8 | PredefinedType | IfcStructuralCurveMemberTypeEnum | Type of member with respect to its load carrying behavior in this analysis idealization. | X | |
| 9 | Axis | IfcDirection |
Direction which is used in the definition of the local z axis. Axis is specified relative to the so-called global coordinate system, i.e. the SELF\IfcProduct.ObjectPlacement.
NOTE It is desirable and usually possible that many instances of IfcStructuralCurveConnection and IfcStructuralCurveMember share a common instance of IfcDirection as their Axis attribute. | X | |
Structural Connectivity
The Structural Connectivity concept template applies to this entity as shown in Table 706.
| ||||
Table 706 — IfcStructuralCurveMember Structural Connectivity |
Material Profile Set Usage
The Material Profile Set Usage concept applies to this entity.
The material of direct instances IfcStructuralCurveMember (in contrast to instances of the subtype IfcStructuralCurveMemberVarying) is defined by IfcMaterialProfileSetUsage and attached by the IfcRelAssociatesMaterial.RelatingMaterial. It is accessible by the inverse HasAssociations relationship. Composite profile beams can be represented by refering to several _IfcMaterialProfile_s within the IfcMaterialProfileSet that is referenced from the IfcMaterialProfileSetUsage. In case of tapered members, the material profile usage subtype IfcMaterialProfileSetUsageDual is used which specifies _IfcMaterialProfileSet_s separately at the start and the end of the tapered member.
The material (IfcMaterial) in each IfcMaterialProfile(Set) is specified minimally by a name which corresponds with an agreed upon standardized structural material designation. An external reference to the source which specifies the material designation should be provided. Alternatively, structural material properties may be provided by means of IfcMechanicalMaterialProperties and IfcExtendedMaterialProperties.
The profile (IfcProfileDef) in each IfcMaterialProfile(Set) is specified minimally by a name which corresponds with an agreed upon standardized structural profile designation. An external reference to the source which specifies the profile designation should be provided. Alternatively or additionally, explicit profile geometry should be provided by using respective subtypes of IfcProfileDef. Alternatively or additionally, structural profile properties may be provided by means of subtypes of IfcProfileProperties.
An IfcProfileDef is a two-dimensional geometric object with a xp,yp coordinate system. The profile is inserted into the curve member model thus that the origin of xp,yp is located at the member's reference curve and that xp,yp are parallel with and directed like the local y,z.
NOTE Due to convention in structural mechanics, axis names of IfcStructuralCurveMember differ from axis names of building elements like IfcBeamStandardCase: The extrusion axis of IfcStructuralCurveMember is called x while the extrusion axis of IfcBeamStandardCase is called z. Hence x,y,z of IfcStructuralCurveMember correspond with z,x,y of IfcBeamStandardCase.
If the profile is meant to be inserted centrically in terms of structural section properties, it is necessary that the origin of xp,yp is identical with the geometric centroid of the profile (commonly also called centre of gravity). If subtypes of IfcParameterizedProfileDef are used which are only singly symmetric or are asymmetric, an explicit translation by IfcParameterizedProfileDef.Position.Location is required then.
If the profile is inserted at its geometric centroid, IfcMaterialProfileSetUsage.CardinalPoint shall be set to 10.
Otherwise, the profile is inserted eccentrically and a different cardinal point should be set accordingly.
NOTE Another eccentricity model is available independently of eccentric profile specification: The reference curve of the member may be located eccentrically relative to the reference points of the connected _IfcStructuralPointConnection_s. The connection relationship is then established by IfcRelConnectsWithEccentricity. Whether one or the other or both eccentricity models may be used is subject to information requirements and local agreements.
Reference Topology
The Reference Topology concept template applies to this entity as shown in Table 707.
| ||
Table 707 — IfcStructuralCurveMember Reference Topology |
Direct instances of IfcStructuralCurveMember shall have a topology representation which consists of one instance of IfcEdge or a subtype, representing the reference curve of the curve member. See definitions at IfcStructuralItem for further specifications.
Informal Propositions:
The local coordinate system is established by the reference curve given by topology representation and by the attribute Axis. The local x axis is parallel with the tangent on the reference curve. The local z axis is located in the surface which is created by sweeping Axis along the reference curve and is directed according to Axis. The local y axis is directed such that x,y,z form a right-handed Cartesian coordinate system.
Instance diagram
<?xml version="1.0" encoding="utf-8"?>
<ConceptRoot xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" uuid="1f707afa-794c-42f2-8bbb-a63fa2e7f642" name="IfcStructuralCurveMember" applicableRootEntity="IfcStructuralCurveMember">
<Applicability>
<Template ref="fb94785e-b47c-40a5-a8d2-81d053fe1b59" />
<TemplateRules operator="and">
</TemplateRules>
</Applicability>
<Concepts>
<Concept uuid="125b09ca-3549-4b39-9238-40e1c666bc2d" name="Structural Connectivity">
<Template ref="f4f75d4f-6d38-4cbe-9efb-dfb58440dfcb" />
<TemplateRules operator="and">
<TemplateRule Description="Point connections at each end of the member." Parameters="StructuralConnection[Type]='IfcStructuralPointConnection'" />
</TemplateRules>
</Concept>
<Concept uuid="c94c3cec-6438-4032-a63c-004cab908945" name="Material Profile Set Usage">
<Template ref="6aa01429-b566-4b36-875a-3162088a9831" />
</Concept>
<Concept uuid="3a6254e4-ed1f-41e3-840e-3eb34032a92a" name="Reference Topology">
<Template ref="79dd6317-2390-44ca-88c2-70d46cd5b969" />
<TemplateRules operator="and">
<TemplateRule Parameters="Topology[Type]='IfcEdge'" />
</TemplateRules>
</Concept>
</Concepts>
</ConceptRoot>
<xs:element name="IfcStructuralCurveMember" type="ifc:IfcStructuralCurveMember" substitutionGroup="ifc:IfcStructuralMember" nillable="true"/>
<xs:complexType name="IfcStructuralCurveMember">
<xs:complexContent>
<xs:extension base="ifc:IfcStructuralMember">
<xs:sequence>
<xs:element name="Axis" type="ifc:IfcDirection" nillable="true"/>
</xs:sequence>
<xs:attribute name="PredefinedType" type="ifc:IfcStructuralCurveMemberTypeEnum" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
ENTITY IfcStructuralCurveMember
SUPERTYPE OF(IfcStructuralCurveMemberVarying)
SUBTYPE OF (IfcStructuralMember);
PredefinedType : IfcStructuralCurveMemberTypeEnum;
Axis : IfcDirection;
WHERE
HasObjectType : (PredefinedType <> IfcStructuralCurveMemberTypeEnum.USERDEFINED) OR EXISTS(SELF\IfcObject.ObjectType);
END_ENTITY;
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