IfcWallStandardCase

IfcWallStandardCase

Definition from IAI: The standard wall (IfcWallStandardCase) defines a wall with certain constraints for the provision of parameter and with certain constraints for the geometric representation. The IfcWallStandardCase handles all cases of walls, that have a single thickness along the path, i.e.:

parallel sides for straight walls
co-centric sides for curved walls.

The following parameter shall be given:

Wall height, taken from the depth of extrusion, provided by the geometric representation.
Wall thickness, taken from the material layer set, attached to the wall
Wall offset from axis, taken from the material layer set, attached to the wall

HISTORY New entity in IFC Release 2x.
ISSUE See issue log for issues raised in IFC Release 2x.

Geometry Use Definitions:

The geometric representation of IfcWallStandard is given by the IfcProductDefinitionShape, allowing multiple geometric representation. Included are:

Local Placement

The use of local placement is defined at the supertype IfcWall.

Geometric Representation

The standard geometric representation of IfcWallStandard is defined using the following multiple shape representations for its definition:

WallAxis: A two-dimensional open curve (IfcBoundedCurve) defining the axis for the standard wall. The material layer offset is measured from the wall axis.
Body: A Swept Solid Representation or a CSG representation defining the 3D shape of the standard wall

First representation: WallAxis

The wall axis is represented by a two-dimensional open curve within a particular shape representation. The wall axis is used to apply the parameter to the wall geometry. The following attribute values shall be used

IfcShapeRepresentation

RepresentationIdentifier : 'WallAxis'

RepresentationType : 'GeometricSet'

	In case of a straight wall, the set of items shall include a single geometric representation item of type IfcPolyline.
	In case of a curved wall, 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 IfcWallStandard is defined by using

SweptSolid representation for walls without clippings
CSG representation for walls with clippings

IfcShapeRepresentation

RepresentationIdentifier : 'WallBody'

RepresentationType : 'SweptSolid' or 'CSG'

SweptSolid representation

The standard geometric representation (for body) of IfcWallStandard 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 co-ordinate system of the referred spatial structure element. It might be further constraint 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 wall is described in the ground view and extruded vertically. The profile (also identical with the foot print of the wall) is defined by the IfcArbitraryProfileDef (excluding its subtypes). The profile is given with all wall connections already resolved.

In case of a straight wall the two sides of the profile shall be parallel to the wall axis, i.e. the wall has a single unchanged thickness.

In case of a curved wall the two sides of the profile shall be parallel (with defined offset) to the wall axis, i.e. the wall has a single unchanged thickness.

The advanced geometric representation (for body) of IfcWallStandard 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.

	Example of clipping using an IfcPolygonalBoundedHalfSpace as SecondOperand in the IfcBooleanClippingResult.
	Example of clipping using an IfcHalfSpaceSolid as SecondOperand in the IfcBooleanClippingResult.

EXPRESS specification:

ENTITY IfcWallStandardCase

SUBTYPE OF (

IfcWall);

WHERE

WR1

SIZEOF (QUERY(temp <* USEDIN(SELF, 'IFCKERNEL.IFCRELASSOCIATES.RELATEDOBJECTS') | ('IFCPRODUCTEXTENSION.IFCRELASSOCIATESMATERIAL' IN TYPEOF(temp)) AND ('IFCMATERIALRESOURCE.IFCMATERIALLAYERSETUSAGE' IN TYPEOF(temp.RelatingMaterial)) )) = 1;

END_ENTITY;

Formal Propositions:

WR1

The IfcWallStandard relies on the provision of an IfcMaterialLayerSetUsage.

References (1):

Name

Type

Referred through

Express-G

IfcWall

Entity

Subtype

Diagram 2

Inheritance graph

ENTITY IfcWallStandardCase;

ENTITY IfcRoot;

GlobalId

IfcGloballyUniqueId;

OwnerHistory

IfcOwnerHistory;

Name

OPTIONAL IfcLabel;

Description

OPTIONAL IfcText;

ENTITY IfcObject;

ObjectType

OPTIONAL IfcLabel;

INVERSE

IsDefinedBy

SET OF IfcRelDefines FOR RelatedObjects;

HasAssociations

SET OF IfcRelAssociates FOR RelatedObjects;

HasAssignments

SET OF IfcRelAssigns FOR RelatedObjects;

Decomposes

SET OF IfcRelDecomposes FOR RelatedObjects;

IsDecomposedBy

SET [0:1] OF IfcRelDecomposes FOR RelatingObject;

ENTITY IfcProduct;

ObjectPlacement

OPTIONAL IfcObjectPlacement;

Representation

OPTIONAL IfcProductRepresentation;

INVERSE

ReferencedBy

SET OF IfcRelAssignsToProduct FOR RelatingProduct;

ENTITY IfcElement;

Tag

OPTIONAL IfcIdentifier;

INVERSE

ConnectedTo

SET OF IfcRelConnectsElements FOR RelatingElement;

ConnectedFrom

SET OF IfcRelConnectsElements FOR RelatedElement;

ContainedInStructure

SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements;

ENTITY IfcBuildingElement;

INVERSE

ProvidesBoundaries

SET OF IfcRelSpaceBoundary FOR RelatedBuildingElement;

HasOpenings

SET OF IfcRelVoidsElement FOR RelatingBuildingElement;

FillsVoids

SET [0:1] OF IfcRelFillsElement FOR RelatedBuildingElement;

ENTITY IfcWall;

ENTITY IfcWallStandardCase;

END_ENTITY;