IFC 4.3.x development

8.8.3.34 IfcSectionedSolidHorizontal

Change log

IFC4X1

added

IFC4X3_RC3

modificationsattributes CrossSectionPositions definitionChanged from list[2:?] of IfcDistanceExpression to list[2:?] of IfcCurveMeasureSelect

8.8.3.34.1 Semantic definitions at the entity

An IfcSectionedSolidHorizontal is a solid model constructed by sweeping potentially varying cross sections along a curve horizontally.

The solid is generated by sweeping the CrossSections between CrossSectionPositions with linear interpolation of profile points, where the profile normal agrees with the tangent of the Directrix, the profile X axis is oriented perpendicularly to the left of the Directrix (same direction as LateralOffset at IfcPointByDistanceExpression) as facing forward along the directrix, and the profile Y axis is oriented upwards according to FixedAxisVertical.

For sections having cross-section rotated according to a single super-elevation, IfcDerivedProfileDef may be used to indicate such rotation with each ParentProfile referring to the same underlying profile. For sections having cross-section transformed according to multiple super-elevations with points varying independently, each profile may be of a different instance but of same type (e.g. IfcArbitraryClosedProfileDef), and may optionally have cross section points associated to string lines (“guide curves”) using IfcIndexedPolyCurve with IfcCartesianPointList2DLabelled.

Figure 1 illustrates four girders of a bridge having a constant parameterized profile, two guardrails having a constant arbitrary profile (one of them mirrored), and a bridge deck having a variable arbitrary profile.

"spatial structure"

Informal Propositions:

  1. No two consecutive sections shall intersect.
  2. If the type of sections is not IfcParameterizedProfileDef (i.e. an arbitrary profile), then the number of points and edges should be the same for two consecutive profiles
  3. If the directrix is not tangent continuous, the resulting solid is created by a miter at half angle between the two segments.
  4. Very sharp edges may result in nearly impossible miter; implementer agreements may define acceptable limits for tangent discontinuity or require the directrix to be tangent continuous.
  5. The directrix shall not intersect

8.8.3.34.1 Attributes

# Attribute Type Description
IfcRepresentationItem
LayerAssignment SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItemsAssignment of the representation item to a single or multiple layer(s). The LayerAssignments can override a LayerAssignments of the IfcRepresentation it is used within the list of Items.

> IFC2x3 CHANGE  The inverse attribute LayerAssignments has been added.

> IFC4 CHANGE  The inverse attribute LayerAssignment has been restricted to max 1. Upward compatibility for file based exchange is guaranteed.
StyledByItem SET [0:1] OF IfcStyledItem FOR Item Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve.



> IFC2x3 CHANGE  The inverse attribute StyledByItem has been added.
IfcGeometricRepresentationItem
IfcSolidModel
Dim INVALID The space dimensionality of this class, it is always 3.
IfcSectionedSolid
1 Directrix IfcCurve The curve used to define the sweeping operation.
2 CrossSections LIST [2:?] OF IfcProfileDef List of cross sections in sequential order along the Directrix.
IfcSectionedSolidHorizontal
3 CrossSectionPositionsLIST [2:?] OF IfcAxis2PlacementLinear List of distance expressions in sequentially increasing order paired with CrossSections, indicating the position of the corresponding section along the Directrix.
4 FixedAxisVertical IfcBoolean Indicates whether Sections are oriented with the Y axis of each profile facing upwards in +Z direction (True), or vertically perpendicular to the Directrix varying according to slope (False).

8.8.3.34.2 Entity inheritance

dot_inheritance IfcSectionedSolidHorizontal IfcSectionedSolidHorizontal IfcSectionedSolid IfcSectionedSolid IfcSectionedSolidHorizontal->IfcSectionedSolid IfcSolidModel IfcSolidModel IfcSectionedSolid->IfcSolidModel IfcSolidModel_children 4 more... IfcSolidModel_children->IfcSolidModel IfcGeometricRepresentationItem IfcGeometricRepresentationItem IfcSolidModel->IfcGeometricRepresentationItem IfcGeometricRepresentationItem_children 24 more... IfcGeometricRepresentationItem_children->IfcGeometricRepresentationItem IfcRepresentationItem IfcRepresentationItem IfcGeometricRepresentationItem->IfcRepresentationItem IfcRepresentationItem_children 3 more... IfcRepresentationItem_children->IfcRepresentationItem

8.8.3.34.3 Formal representations

ENTITY IfcSectionedSolidHorizontal
 SUBTYPE OF (IfcSectionedSolid);
	CrossSectionPositions : LIST [2:?] OF IfcAxis2PlacementLinear;
	FixedAxisVertical : IfcBoolean;
 WHERE
	CorrespondingSectionPositions : SIZEOF(CrossSections) = SIZEOF(CrossSectionPositions);
	NoLongitudinalOffsets : SIZEOF(QUERY(temp <* CrossSectionPositions | EXISTS(temp.Location.OffsetLongitudinal))) = 0;
END_ENTITY;