IFC 4.3.x development

8.15.3.4 IfcAsymmetricIShapeProfileDef

Change log

IFC4

additions attributes BottomFlangeEdgeRadius
additions attributes BottomFlangeFilletRadius
additions attributes BottomFlangeSlope
additions attributes BottomFlangeWidth
additions attributes OverallDepth
additions attributes TopFlangeEdgeRadius
additions attributes TopFlangeFilletRadius
additions attributes TopFlangeSlope
additions where_rules ValidBottomFilletRadius
additions where_rules ValidFlangeThickness
additions where_rules ValidTopFilletRadius
additions where_rules ValidWebThickness
modificationsattributes CentreOfGravityInY is_optional Changed from True to False
modificationsattributes CentreOfGravityInY name Changed from CentreOfGravityInY to BottomFlangeThickness
modificationsattributes TopFlangeFilletRadius is_optionalChanged from True to False
modificationsattributes TopFlangeFilletRadius name Changed from TopFlangeFilletRadius to WebThickness
modificationssupertype Changed from IfcIShapeProfileDef to IfcParameterizedProfileDef

8.15.3.4.1 Semantic definitions at the entity

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.

HISTORY  New entity in IFC2x2.

IFC2x3 CHANGE  All profile origins are now in the center of the bounding box. The attribute CentreOfGravityInY has been made OPTIONAL.

IFC4 CHANGE  Supertype changed from IfcIShapeProfileDef to IfcParameterizedProfileDef. Attributes which were inherited from IfcIShapeProfileDef are now defined directly at IfcAsymmetricIShapeProfileDef and have been partially renamed but were not reordered.
Bottom flange may be narrower than top flange.
Type of TopFlangeFilletRadius relaxed to allow for zero radius.
Trailing attribute CentreOfGravityInY deleted, use respective property in IfcExtendedProfileProperties instead.
Attributes BottomFlangeEdgeRadius, BottomFlangeSlope, TopFlangeEdgeRadius, TopFlangeSlope added.

Figure 1 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"

8.15.3.4.1 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_.
HasExternalReference SET [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.
IfcAsymmetricIShapeProfileDef
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 BottomFlangeFilletRadiusOPTIONAL 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.

8.15.3.4.2 Entity inheritance

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

8.15.3.4.3 Definitions applying to General Usage

8.15.3.4.3.1 Property Sets for Objects

PsetName
'Pset_ProfileMechanical'

8.15.3.4.4 Formal representations

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
	ValidFlangeThickness : NOT(EXISTS(TopFlangeThickness)) OR ((BottomFlangeThickness + TopFlangeThickness) < OverallDepth);
	ValidWebThickness : (WebThickness < BottomFlangeWidth) AND (WebThickness < TopFlangeWidth);
	ValidBottomFilletRadius : (NOT(EXISTS(BottomFlangeFilletRadius))) OR 
(BottomFlangeFilletRadius <= (BottomFlangeWidth - WebThickness)/2.);
	ValidTopFilletRadius : (NOT(EXISTS(TopFlangeFilletRadius))) OR 
(TopFlangeFilletRadius <= (TopFlangeWidth - WebThickness)/2.);
END_ENTITY;