IFC 4.3.0.1 (IFC4X3_TC1)

# 8.8.3.34 IfcSectionedSolidHorizontal

## 8.8.3.34.1 Semantic definition

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 between profile points with the same tag along the directrix. The profile normal is derived from the associated IfcAxis2PlacementLinear, not necessarily the tangent of the Directrix. The profile X axis is the direction of RefDirection from IfcAxis2PlacementLinear, and the profile Y axis is the direction of Axis.

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") by matching labels using IfcIndexedPolyCurve with IfcCartesianPointList2D.TagList.

Figure 8.8.3.34.A 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.

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

## 8.8.3.34.5 Formal representation

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

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