IFC 4.3.0.1 (IFC4X3) development

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:

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 IfcExtendedProfileProperties, if provided, is negative.

asymmetric I shape profile
Figure 8.15.3.4.A — Asymmetric I-shape profile

8.15.3.4.2 Entity inheritance

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.

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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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:

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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

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8.15.3.4.9 Changelog

  • attribute, BottomFlangeEdgeRadius
  • attribute, BottomFlangeFilletRadius
  • attribute, BottomFlangeSlope
  • attribute, BottomFlangeWidth
  • attribute, OverallDepth
  • attribute, TopFlangeEdgeRadius
  • attribute, TopFlangeFilletRadius
  • attribute, TopFlangeSlope
  • where rule, ValidBottomFilletRadius
  • where rule, ValidFlangeThickness
  • where rule, ValidTopFilletRadius
  • where rule, ValidWebThickness
  • attribute CentreOfGravityInY name, Changed from "CentreOfGravityInY" to "BottomFlangeThickness"
  • attribute CentreOfGravityInY optional, Changed from "True" to "False"
  • attribute TopFlangeFilletRadius name, Changed from "TopFlangeFilletRadius" to "WebThickness"
  • attribute TopFlangeFilletRadius optional, Changed from "True" to "False"
  • supertype, Changed from "IfcIShapeProfileDef" to "IfcParameterizedProfileDef"