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Definition from buildingSMART: Instances of the entity IfcStructuralCurveMember shall be used to describe linear structural elements. Profile and material properties are defined by using objectified relationships:

HISTORY: New entity in Release IFC2x Edition 2.

Use Definition

curve member
The topological (or axis) representation of the structural curve member is given by assigning an edge through the general Representation capability inherited by IfcProduct.

For linear structural curve members the use of IfcEdge is sufficient, since a linear interpolation between the two vertices is assumed, if the structural curve member is an arc, or other non-linear form, the IfcEdgeCurve needs to be used instead, having the geometric form of the curve between the two vertices fully defined.

A single, constant, profile definition is assigned to the structural curve member through the IfcRelAssociatedProfileProperties.

Topology Use Definition

Instances of IfcStructuralCurveMember shall have a topology representation. It includes a placement and a product representation. The IfcProductRepresentation shall be given by an item of Representations being of type "IfcTopologyRepresentation".


The placement for IfcStructuralCurveMember is determined at its supertype IfcProduct. It is defined by the optional IfcObjectPlacement, referenced by ObjectPlacement at IfcProduct, which establishes, if given, the object coordinate system that is referenced by all topological representations of that product.

Topology Representation

Instances of IfcStructuralCurveMember shall have a topology representation given by an edge with an optional additional geometric representation of the included curve. It can be provided by either

which should be the single item of IfcTopologyRepresentation.Items. The IfcEdge might be referenced by two or many IfcSubedge, representing sections of the IfcStructuralCurveMember with changing properties. See subtype IfcStructuralCurveMemberVarying for the use definition.

EXPRESS specification:

ENTITY IfcStructuralCurveMember
SUPERTYPE OF (IfcStructuralCurveMemberVarying)
SUBTYPE OF ( IfcStructuralMember);
PredefinedType  :  IfcStructuralCurveTypeEnum;

Attribute definitions:

PredefinedType  :  Defines the type of the structural curve member.

Inheritance graph

ENTITY IfcStructuralCurveMember;
GlobalId  :  IfcGloballyUniqueId;
OwnerHistory  :  IfcOwnerHistory;
Name  :  OPTIONAL IfcLabel;
Description  :  OPTIONAL IfcText;
ENTITY IfcObjectDefinition;
HasAssignments  :  SET OF IfcRelAssigns FOR RelatedObjects;
IsDecomposedBy  :  SET OF IfcRelDecomposes FOR RelatingObject;
Decomposes  :  SET [0:1] OF IfcRelDecomposes FOR RelatedObjects;
HasAssociations  :  SET OF IfcRelAssociates FOR RelatedObjects;
ENTITY IfcObject;
ObjectType  :  OPTIONAL IfcLabel;
IsDefinedBy  :  SET OF IfcRelDefines FOR RelatedObjects;
ENTITY IfcProduct;
ObjectPlacement  :  OPTIONAL IfcObjectPlacement;
Representation  :  OPTIONAL IfcProductRepresentation;
ReferencedBy  :  SET OF IfcRelAssignsToProduct FOR RelatingProduct;
ENTITY IfcStructuralItem;
AssignedStructuralActivity  :  SET OF IfcRelConnectsStructuralActivity FOR RelatingElement;
ENTITY IfcStructuralMember;
ReferencesElement  :  SET OF IfcRelConnectsStructuralElement FOR RelatedStructuralMember;
ConnectedBy  :  SET OF IfcRelConnectsStructuralMember FOR RelatingStructuralMember;
ENTITY IfcStructuralCurveMember;
PredefinedType  :  IfcStructuralCurveTypeEnum;