IFC 4.3.x development

8.15.3.6 IfcCenterLineProfileDef

8.15.3.6.1 Semantic definitions at the entity

The profile IfcCenterLineProfileDef defines an arbitrary two-dimensional open, not self intersecting profile for the use within the swept solid geometry. It is given by an area defined by applying a constant thickness to a centerline, generating an area from which the solid can be constructed.

Among else, IfcCenterLineProfileDef is used to model cold-formed steel or aluminium sections (Sigma, Zeta, Omega, and similar sections which are not covered by subtypes of IfcParameterizedProfileDef). However, since IfcCenterLineProfileDef does not provide shape parameters except for the thickness, there is generally a need to further specify the profile definition by means of

  • the name,
  • external reference to a document or library,
  • profile properties,

or a combination of them. See IfcProfileDef for guidance on external references for profiles.

HISTORY  New entity in IFC2x3.

Informal Propositions:

  1. The Curve has to be an open curve.
  2. The Curve has to be a non-intersecting curve.

Figure 1 illustrates the center line profile definition. The Curve is defined in the underlying coordinate system. The underlying coordinate system is defined by the swept surface that uses the profile definition. It is the xy plane of:

The Curve attribute defines a two dimensional open bounded curve. The Thickness attribute defines a constant thickness along the curve.

"center line"

8.15.3.6.1 Attributes

# Attribute Type Description
IfcProfileDef
1 ProfileType IfcProfileTypeEnum Defines the type of geometry into which this profile definition shall be resolved, either a curve or a surface area. In case of curve the profile should be referenced by a swept surface, in case of area the profile should be referenced by a swept area solid.
2 ProfileName OPTIONAL IfcLabel Human-readable name of the profile, for example according to a standard profile table. As noted above, machine-readable standardized profile designations should be provided in _IfcExternalReference.ItemReference_.
HasExternalReferenceSET [0:?] OF IfcExternalReferenceRelationship FOR RelatedResourceObjectsReference to external information, e.g. library, classification, or document information, which is associated with the profile.

> IFC4 CHANGE New inverse attribute
HasProperties SET [0:?] OF IfcProfileProperties FOR ProfileDefinition Additional properties of the profile, for example mechanical properties.

> IFC4 CHANGE New inverse attribute
IfcArbitraryOpenProfileDef
3 Curve IfcBoundedCurve Open bounded curve defining the profile.
IfcCenterLineProfileDef
4 Thickness IfcPositiveLengthMeasure Constant thickness applied along the center line.

8.15.3.6.2 Entity inheritance

dot_inheritance IfcCenterLineProfileDef IfcCenterLineProfileDef IfcArbitraryOpenProfileDef IfcArbitraryOpenProfileDef IfcCenterLineProfileDef->IfcArbitraryOpenProfileDef IfcProfileDef IfcProfileDef IfcArbitraryOpenProfileDef->IfcProfileDef IfcProfileDef_children 5 more... IfcProfileDef_children->IfcProfileDef

8.15.3.6.3 Definitions applying to General Usage

8.15.3.6.3.1 Property Sets for Objects

PsetName
'Pset_ProfileMechanical'

8.15.3.6.4 Formal representations

ENTITY IfcCenterLineProfileDef
 SUBTYPE OF (IfcArbitraryOpenProfileDef);
	Thickness : IfcPositiveLengthMeasure;
END_ENTITY;