IFC (IFC4X3) development IfcLShapeProfileDef Semantic definition

IfcLShapeProfileDef defines a section profile that provides the defining parameters of an L-shaped section (equilateral L profiles are also covered by this entity) to be used by the swept area solid. Its parameters and orientation relative to the position coordinate system are according to the following illustration. The shorter leg has the same direction as the positive Position.P[1]-axis, the longer or equal leg the same as the positive Position.P[2]-axis. The centre of the position coordinate system is in the profiles centre of the bounding box.

Figure and Figure illustrates parameters of equal-sided and non-equal sided L-shaped section definitions.

non equal sided L-shape
Figure — Non-equal L-shape profile

The parameterized profile defines its own position coordinate system. The underlying coordinate system is defined by the swept area solid that uses the profile definition. It is the xy plane of IfcSweptAreaSolid.Position by using offsets of the position location, the parameterized profile can be positioned centric (using x,y offsets = 0.), or at any position relative to the profile.

In the illustrated example, the 'CentreOfGravityInX' and 'CentreOfGravityInY' properties in IfcExtendedProfileProperties, if provided, are both negative.

equal sided L-shape
Figure — Equal L-shape profile

The profile is inserted into the underlying coordinate system of the swept area solid by using the Position attribute. In this example (cardinal point of gravity) the attribute values of IfcAxis2Placement2D are:

Location = IfcCartesianPoint(+|CentreOfGravityInX|, +|CentreOfGravityInY|)
RefDirection = NIL (defaults to 1.,0.)

In the illustrated example, the x and y value of Position.Location, i.e. the measures |CentreOfGravityInX| and |CentreOfGravityInY| are both positive. On the other hand, the properties named 'CentreOfGravityInX' and 'CentreOfGravityInY' in IfcExtendedProfileProperties, if provided, must both be set to 0 now because the centre of gravity of the resulting profile definition is located in the coordinate origin. Entity inheritance Attributes

# Attribute Type Description
IfcProfileDef (4)
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.

HasExternalReference SET [0:?] OF IfcExternalReferenceRelationship FOR RelatedResourceObjects

Reference to external information, e.g. library, classification, or document information, which is associated with the profile.

HasProperties SET [0:?] OF IfcProfileProperties FOR ProfileDefinition

Additional properties of the profile, for example mechanical properties.

IfcParameterizedProfileDef (1)
3 Position OPTIONAL IfcAxis2Placement2D

Position coordinate system of the parameterized profile definition. If unspecified, no translation and no rotation is applied.

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IfcLShapeProfileDef (6)
4 Depth IfcPositiveLengthMeasure

Leg length, see illustration above (= h). Same as the overall depth.

5 Width OPTIONAL IfcPositiveLengthMeasure

Leg length, see illustration above (= b). Same as the overall width. This attribute is formally optional for historic reasons only. Whenever the width is known, it shall be provided by value.

6 Thickness IfcPositiveLengthMeasure

Constant wall thickness of profile, see illustration above (= ts).

7 FilletRadius OPTIONAL IfcNonNegativeLengthMeasure

Fillet radius according the above illustration (= r1).

8 EdgeRadius OPTIONAL IfcNonNegativeLengthMeasure

Edge radius according the above illustration (= r2).

9 LegSlope OPTIONAL IfcPlaneAngleMeasure

Slope of the inner face of each leg of the profile.

Table Formal propositions

Name Description

The thickness shall be smaller than the depth and width.

(Thickness < Depth) AND (NOT(EXISTS(Width)) OR (Thickness < Width))
Table Property sets

  • Pset_ProfileMechanical
    • MassPerLength
    • CrossSectionArea
    • Perimeter
    • MinimumPlateThickness
    • MaximumPlateThickness
    • CentreOfGravityInX
    • CentreOfGravityInY
    • ShearCentreZ
    • ShearCentreY
    • MomentOfInertiaY
    • MomentOfInertiaZ
    • MomentOfInertiaYZ
    • TorsionalConstantX
    • WarpingConstant
    • ShearDeformationAreaZ
    • ShearDeformationAreaY
    • MaximumSectionModulusY
    • MinimumSectionModulusY
    • MaximumSectionModulusZ
    • MinimumSectionModulusZ
    • TorsionalSectionModulus
    • ShearAreaZ
    • ShearAreaY
    • PlasticShapeFactorY
    • PlasticShapeFactorZ Concept usage

Concept Usage Description
IfcProfileDef (1)
Property Sets for Profiles General

This concept can be applied to the following resources:

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Table Formal representation

ENTITY IfcLShapeProfileDef
 SUBTYPE OF (IfcParameterizedProfileDef);
	Depth : IfcPositiveLengthMeasure;
	Width : OPTIONAL IfcPositiveLengthMeasure;
	Thickness : IfcPositiveLengthMeasure;
	FilletRadius : OPTIONAL IfcNonNegativeLengthMeasure;
	EdgeRadius : OPTIONAL IfcNonNegativeLengthMeasure;
	LegSlope : OPTIONAL IfcPlaneAngleMeasure;
	ValidThickness : (Thickness < Depth) AND (NOT(EXISTS(Width)) OR (Thickness < Width));
END_ENTITY; References

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