Definition from IAI: A segment of a flow distribution system that is typically straight, contiguous and has two ports (e.g., a section of pipe or duct).
The following parameters shall be given:
- Segment length, taken from the FinishedLength attribute in the Pset, provides the depth of the extrusion.
- Segment profile dimensions, taken from the IfcConnectionPortGeometry attached to the segment.
HISTORY: New entity in IFC R2.0.
ISSUES: See issues and change log for changes made in IFC R2x.
Geometry Use Definitions
The geometric representation of IfcFlowSegment is given by the IfcProductDefinitionShape, allowing multiple geometric representations. Included are:
Local Placement
The use of local placement is defined at the supertype IfcDistributionFlowElement.
Geometric Representation
The standard geometric representation of IfcFlowSegment is defined using the following multiple shape representations for its definition:
- SegmentAxis: A two-dimensional open curve (IfcBoundedCurve) defining the axis for the segment.
- Body: A Swept Solid Representation or a CSG representation defining the 3D shape of the segment.
First representation: SegmentAxis
The segment axis is represented by a two-dimensional open curve within a particular shape representation. The segment axis is used to apply the segment length parameter to the segment geometry. The following attribute values shall be used
IfcShapeRepresentation
- RepresentationIdentifier : 'SegmentAxis'
- RepresentationType : 'GeometricSet'
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In case of a straight segment, the set of items shall include a single geometric representation item of type IfcPolyline. In case of a curved segment, the set of items shall include a single geometric representation item of type IfcTrimmedCurve. The curve shall have a BasisCurve of type IfcCircle. |
Second representation: Body
The body of the IfcFlowSegment is defined by using
- SweptSolid representation for segments without clippings.
- CSG representation for segments with clippings.
IfcShapeRepresentation
- RepresentationIdentifier : 'SegmentBody'
- RepresentationType : 'SweptSolid' or 'CSG'
SweptSolid representation
The standard geometric representation (for body) of IfcFlowSegment is defined using the swept solid representation. The following additional constraints apply to the swept solid representation:
- Solid: IfcExtrudedAreaSolid is required,
- Profile: IfcArbitraryProfileDef shall be supported.
- Extrusion: The profile shall be extruded vertically, i.e., in the direction of the z-axis of the coordinate system of the referred spatial structure element. It might be further constrained to be in the direction of the global z-axis in implementers agreements. The extrusion axis shall be perpendicular to the swept profile, i.e. pointing into the direction of the z-axis of the Position of the IfcExtrudedAreaSolid.
The profile of a segment is described in
the ground view and extruded vertically. The profile (also identical with the
foot print of the segment) is defined by the IfcArbitraryProfileDef (excluding its
subtypes). The profile is given with all segment connections already resolved.
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The advanced geometric representation (for body) of IfcFlowSegment is defined using the CSG representation. The following additional constraints apply to the swept solid representation:
- Solid: see standard geometric representation
- Profile: see standard geometric representation
- Extrusion: see standard geometric representation
- Boolean result: The IfcBooleanClippingResult shall be supported, allowing for Boolean differences between the swept solid (here IfcExtrudedAreaSolid) and one or several IfcHalfSpaceSolid.
B-Rep Representation
The faceted B-Rep capabilities (with or without voids) shall be supported for B-Rep representation.