Definition from buildingSMART: Instances of the entity IfcStructuralCurveMemberVarying shall be used to describe linear structural elements with varying profile properties.
The varying profile properties are assigned through the IfcRelAssociatesProfileProperties with an additional link to the IfcShapeAspect, which relates the profile properties to the different vertices of the structural curve member.
HISTORY: New entity in Release IFC2x Edition 2.
varying profiles along the longitudinal axis are assigned by using
several relationships of IfcRelAssociatesProfileProperties,
each assigning one profile definition (IfcProfileProperties
optionally referencing one IfcProfileDef)
to a vertex along the longitudial axis.
The topological representation is an IfcEdge, decomposed into IfcSubEdge's, a changing profile definition is associated to the start or end vertex of the IfcSubEdge.
Topology Use Definition
Instances of IfcStructuralCurveMemberVarying 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 guidelines on using the location and topological representation capabilities are identical with the supertype IfcStructuralCurveMember. The additional requirement is that if the varying profile not only has different (morphing) profiles at the start and end edge, then the IfcTopologyRepresentation.Item shall be an IfcEdge (or IfcEdgeCurve, IfcOrientedEdge) that is referenced by the Parent attribute of at least two IfcSubedge's.
Shape Aspect Use Definition
The attribute HasAssociations references a set of IfcRelAssociatesProfileProperties, each referring to an IfcShapeAspect, that has a list of ShapeRepresentations. Each individual IfcShapeRepresentation within that list shall have a single (or two) item(s) within its list of Items. The type of the item shall be:
It references either a start or an end vertex (or both) to which the profile properties apply.