8.15.3.4 IfcAsymmetricIShapeProfileDef

8.15.3.4.1 Semantic definition

IfcAsymmetricIShapeProfileDef defines a section profile that provides the defining parameters of a singly symmetric I-shaped section. Its parameters and orientation relative to the position coordinate system are according to the following illustration. The centre of the position coordinate system is in the profile's centre of the bounding box.

The overall width of the profile is implicitly given by the maximum of the bottom flange width and the top flange width.

IfcAsymmetricIShapeProfileDef can also be used to model rail profiles if the application scenario does not require a full explicit shape model of the rail profile. Alternatively, IfcArbitraryClosedProfileDef can be used to provide the exact shape of rail profiles. Either way, a reference to an external document or library should be provided to further define the profile as described at IfcProfileDef.

Figure 8.15.3.4.A illustrates parameters of the asymmetric I-shaped section definition. 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. The parameterized profile is defined by a set of parameter attributes. In the illustrated example, the 'CentreOfGravityInY' property in IfcProfileProperties, if provided, is negative.

Figure 8.15.3.4.A — Asymmetric I-shape profile

8.15.3.4.2 Entity inheritance

- IfcProfileDef

8.15.3.4.3 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. 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 (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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IfcAsymmetricIShapeProfileDef (12)
4	BottomFlangeWidth	IfcPositiveLengthMeasure	Extent of the bottom flange, defined parallel to the x axis of the position coordinate system.
5	OverallDepth	IfcPositiveLengthMeasure	Total extent of the depth, defined parallel to the y axis of the position coordinate system.
6	WebThickness	IfcPositiveLengthMeasure	Thickness of the web of the I-shape. The web is centred on the x-axis and the y-axis of the position coordinate system.
7	BottomFlangeThickness	IfcPositiveLengthMeasure	Flange thickness of the bottom flange.
8	BottomFlangeFilletRadius	OPTIONAL IfcNonNegativeLengthMeasure	The fillet between the web and the bottom flange. 0 if sharp-edged, omitted if unknown.
9	TopFlangeWidth	IfcPositiveLengthMeasure	Extent of the top flange, defined parallel to the x axis of the position coordinate system.
10	TopFlangeThickness	OPTIONAL IfcPositiveLengthMeasure	Flange thickness of the top flange. This attribute is formally optional for historic reasons only. Whenever the flange thickness is known, it shall be provided by value.
11	TopFlangeFilletRadius	OPTIONAL IfcNonNegativeLengthMeasure	The fillet between the web and the top flange. 0 if sharp-edged, omitted if unknown.
12	BottomFlangeEdgeRadius	OPTIONAL IfcNonNegativeLengthMeasure	Radius of the upper edges of the bottom flange. 0 if sharp-edged, omitted if unknown.
13	BottomFlangeSlope	OPTIONAL IfcPlaneAngleMeasure	Slope of the upper faces of the bottom flange. Non-zero in case of of tapered bottom flange, 0 in case of parallel bottom flange, omitted if unknown.
14	TopFlangeEdgeRadius	OPTIONAL IfcNonNegativeLengthMeasure	Radius of the lower edges of the top flange. 0 if sharp-edged, omitted if unknown.
15	TopFlangeSlope	OPTIONAL IfcPlaneAngleMeasure	Slope of the lower faces of the top flange. Non-zero in case of of tapered top flange, 0 in case of parallel top flange, omitted if unknown.

Table 8.15.3.4.B

8.15.3.4.4 Formal propositions

Name	Description
ValidBottomFilletRadius	The bottom fillet radius, if given, shall be within the range of allowed values.
`(NOT(EXISTS(BottomFlangeFilletRadius))) OR (BottomFlangeFilletRadius <= (BottomFlangeWidth - WebThickness)/2.)`
ValidFlangeThickness	The sum of flange thicknesses shall be less than the overall depth.
`NOT(EXISTS(TopFlangeThickness)) OR ((BottomFlangeThickness + TopFlangeThickness) < OverallDepth)`
ValidTopFilletRadius	The top fillet radius, if given, shall be within the range of allowed values.
`(NOT(EXISTS(TopFlangeFilletRadius))) OR (TopFlangeFilletRadius <= (TopFlangeWidth - WebThickness)/2.)`
ValidWebThickness	The web thickness shall be less than either flange width.
`(WebThickness < BottomFlangeWidth) AND (WebThickness < TopFlangeWidth)`

Table 8.15.3.4.C

8.15.3.4.5 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

8.15.3.4.6 Concept usage

Concept	Usage	Description
IfcProfileDef (1)
Property Sets for Profiles	General	This concept can be applied to the following resources: Pset_ProfileMechanical
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Concept

Usage

Description

IfcProfileDef (1)

Property Sets for Profiles

General

This concept can be applied to the following resources:

Pset_ProfileMechanical

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Table 8.15.3.4.D

8.15.3.4.7 Formal representation

ENTITY IfcAsymmetricIShapeProfileDef
 SUBTYPE OF (IfcParameterizedProfileDef);
	BottomFlangeWidth : IfcPositiveLengthMeasure;
	OverallDepth : IfcPositiveLengthMeasure;
	WebThickness : IfcPositiveLengthMeasure;
	BottomFlangeThickness : IfcPositiveLengthMeasure;
	BottomFlangeFilletRadius : OPTIONAL IfcNonNegativeLengthMeasure;
	TopFlangeWidth : IfcPositiveLengthMeasure;
	TopFlangeThickness : OPTIONAL IfcPositiveLengthMeasure;
	TopFlangeFilletRadius : OPTIONAL IfcNonNegativeLengthMeasure;
	BottomFlangeEdgeRadius : OPTIONAL IfcNonNegativeLengthMeasure;
	BottomFlangeSlope : OPTIONAL IfcPlaneAngleMeasure;
	TopFlangeEdgeRadius : OPTIONAL IfcNonNegativeLengthMeasure;
	TopFlangeSlope : OPTIONAL IfcPlaneAngleMeasure;
 WHERE
	ValidBottomFilletRadius : (NOT(EXISTS(BottomFlangeFilletRadius))) OR 
(BottomFlangeFilletRadius <= (BottomFlangeWidth - WebThickness)/2.);
	ValidFlangeThickness : NOT(EXISTS(TopFlangeThickness)) OR ((BottomFlangeThickness + TopFlangeThickness) < OverallDepth);
	ValidTopFilletRadius : (NOT(EXISTS(TopFlangeFilletRadius))) OR 
(TopFlangeFilletRadius <= (TopFlangeWidth - WebThickness)/2.);
	ValidWebThickness : (WebThickness < BottomFlangeWidth) AND (WebThickness < TopFlangeWidth);
END_ENTITY;

8.15.3.4.8 References

IfcParameterizedProfileDef