IFC 4.3.x development

8.15.3.13 IfcLShapeProfileDef

Change log

IFC4

additions where_rules ValidThickness
deletions attributes CentreOfGravityInX
deletions attributes CentreOfGravityInY
deletions where_rules WR21
deletions where_rules WR22
modificationsattributes EdgeRadius definition Changed from IfcPositiveLengthMeasure to IfcNonNegativeLengthMeasure
modificationsattributes FilletRadius definitionChanged from IfcPositiveLengthMeasure to IfcNonNegativeLengthMeasure

8.15.3.13.1 Semantic definitions at the entity

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.

HISTORY  New entity in IFC2x2.

IFC2x3 CHANGE  All profile origins are now in the center of the bounding box.

IFC4 CHANGE  Types of FilletRadius and EdgeRadius were relaxed to allow for zero values.
Trailing attributes CentreOfGravityInX and CentreOfGravityInY deleted, use respective properties in IfcExtendedProfileProperties instead.
WHERE rule which required Width <= Depth removed.

Figure 1 illustrates parameters of equal-sided and non-equal sided L-shaped section definitions.

non equal sided L-shape

Position
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:

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
Note: The black coordinate axes show the underlying coordinate system of the swept surface or swept area solid

Position
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.

Figure 1 — L-shape profile

8.15.3.13.1 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

IfcParameterizedProfileDef
3 Position OPTIONAL IfcAxis2Placement2D Position coordinate system of the parameterized profile definition. If unspecified, no translation and no rotation is applied.
IfcLShapeProfileDef
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.

8.15.3.13.2 Entity inheritance

dot_inheritance IfcLShapeProfileDef IfcLShapeProfileDef IfcParameterizedProfileDef IfcParameterizedProfileDef IfcLShapeProfileDef->IfcParameterizedProfileDef IfcParameterizedProfileDef_children 10 more... IfcParameterizedProfileDef_children->IfcParameterizedProfileDef IfcProfileDef IfcProfileDef IfcParameterizedProfileDef->IfcProfileDef IfcProfileDef_children 5 more... IfcProfileDef_children->IfcProfileDef

8.15.3.13.3 Definitions applying to General Usage

8.15.3.13.3.1 Property Sets for Objects

PsetName
'Pset_ProfileMechanical'

8.15.3.13.4 Formal representations

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