#### 6.1.3.13 IfcWallStandardCase

| Wand - Standard
| Mur standard

The IfcWallStandardCase defines a wall with certain constraints for the provision of parameters and with certain constraints for the geometric representation. The IfcWallStandardCase handles all cases of walls, that are extruded vertically:

- along the positive z axis of the wall object coordinate system, and
- along the positve z axis of the global (world) coordinate system

and have a single thickness along the path for each wall layer, i.e.:

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

and have either:

- a straight line axis (straight wall), or
- a circular arc axis (round wall).

and shall not have

- aggregated components, that is, parts aggregated to a wall by IfcRelAggregates
- shape representation for 'Body' not being an extrusion, or clipped extrusion

The following parameter have to be provided:

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

The IfcWallStandardCase requires the provision of the wall axis either a straight line that is parallel to the x-axis of the object coordinate system, or a circular arc where the tangent at start is parallel to the x-axis of the object coordinate system. The direction of the wall axis shall be the positive direction of that x-axis.

The material of the wall is defined by the IfcMaterialLayerSetUsage and is attached by the IfcRelAssociatesMaterial objectified relationship. It is accessible by the inverse HasAssociations relationship. The material layer set usage has to be given (enforced by where rule).

> HISTORY New entity in IFC2x.

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

- Axis: 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

> NOTE It is invalid to exhange a 'SurfaceModel', or 'Brep' or 'MappedRepresentation' representation for the 'Body' shape representation of an IfcWallStandardCase.

## Plumbing System Design

The following concepts are inherited at supertypes:

- IfcWall: Path Connectivity, Voiding

Instance diagram

Identity

The Identity concept applies to this entity.

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Object Typing

The Object Typing concept applies to this entity as shown in Table 44.

Type
IfcWallType
Table 44 — IfcWallStandardCase Object Typing

The IfcWallType should have a unique IfcMaterialLayerSet, that is referenced by the IfcMaterialLayerSetUsage assigned to all occurrences of this IfcWallType.

Figure 114 illustrates assignment of IfcMaterialLayerSetUsage and IfcMaterialLayerSet to the wall type and the wall occurrence.

Figure 114 — Wall Standard Object Typing

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Material Layer Set Usage

The Material Layer Set Usage concept applies to this entity.

The material of the IfcWallStandardCase is defined by IfcMaterialLayerSetUsage and attached by the IfcRelAssociatesMaterial.RelatingMaterial. It is accessible by the inverse HasAssociations relationship. Multi-layer walls can be represented by refering to several IfcMaterialLayer's within the IfcMaterialLayerSet that is referenced from the IfcMaterialLayerSetUsage.

Material information can also be given at the IfcWallType, defining the common attribute data for all occurrences of the same type. It is then accessible by the inverse IsDefinedBy relationship pointing to IfcSlabType.HasAssociations and via IfcRelAssociatesMaterial.RelatingMaterial. See Type Use Definition for additional agreements for standard slabs.

Figure 115 illustrates material layer usage, where the following conventions shall be met:

- The reference coordinate system is the local coordinate system established by the ObjectPlacement of the IfcWallStandardCase.
- The reference axis is the axis defined by the IfcShapeRepresentation with RepresentationType='Axis' as one of the Representation.Representations of the IfcWallStandardCase.
- The IfcMaterialLayerSetUsage.OffsetFromReferenceLine is given as a distance from this axis.
- The IfcMaterialLayerSetUsage.OffsetFromReferenceLine is the distance parallel to the reference axis and always within the base (XY) plane of the reference coordinate system. A positve value of IfcMaterialLayerSetUsage.OffsetFromReferenceLine would then point into the positive y-axis of the reference coordinate system.
- The IfcMaterialLayerSetUsage.DirectionSense defines how the IfcMaterialLayer's are assigned to the reference axis. POSITIVE means in direction to the positive y-axis of the reference coordinate system.
- The Thickness of each IfcMaterialLayer is provided starting from the OffsetFromReferenceLine and in the direction given by DirectionSense. It is applied without any gap or overlap between two consecutive layers. The TotalThickness of the IfcMaterialLayerSet is the sum of all layer thicknesses.
- The IfcMaterialLayerSetUsage.LayerSetDirection is always AXIS2.

Figure 115 — Wall material layers

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Axis Geometry

The Axis Geometry concept applies to this entity as shown in Table 45.

RepresentationType | Geometry
--- | ---
Curve2D | IfcBoundedCurve
Table 45 — IfcWallStandardCase Axis Geometry

The wall axis is represented by a two-dimensional open curve within a particular shape representation. The wall axis is used to apply the material layer set usage parameter to the wall geometry.

Figure 116 illustrates an axis representation for a straight wall. In case of a straight wall, the set of items shall include a single geometric representation item of type IfcPolyline or IfcTrimmedCurve with the BasisCurve being an IfcLine. The IfcPolyline or IfcTrimmedCurve shall be parallel (here in a special case co-linear) to the x-axis of the object coordinate system. The direction shall be identical to the direction of the x-axis.

Figure 117 illustrates an axis representation for a curved wall. 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. The tangent of the IfcTrimmedCurve shall be parallel at start to the x-axis of the object coordinate system. The direction shall be identical to the direction of the x-axis.

Figure 116 — Wall axis straight | Figure 117 — Wall axis curved

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Body Geometry

The Body Geometry concept applies to this entity as shown in Table 46.

RepresentationType | Geometry
--- | ---
SweptSolid | IfcExtrudedAreaSolid
Clipping | IfcBooleanClippingResult
Table 46 — IfcWallStandardCase Body Geometry

The body representation of IfcWallStandardCase is defined by using 'SweptSolid' representation for walls without clippings or 'Clipping' representation for walls with clippings (e.g. under sloped roof slabs).

SweptSolid Representation Type

The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

- RepresentationIdentifier : 'Body'
- RepresentationType : 'SweptSolid'

The following additional constraints apply to the 'SweptSolid' representation:

- Solid: IfcExtrudedAreaSolid is required,
- Profile: IfcArbitraryClosedProfileDef and IfcRectangleProfileDef 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 IfcArbitraryClosedProfileDef (excluding its subtypes). The profile is given with all wall connections already resolved.

Figure 118 illustrates a body representation for a straight wall. In case of a straight wall, the two sides of the profile shall be parallel to the wall axis, that is, the wall has a single unchanged thickness.

Figure 119 illustrates a body representation for a curved wall. In case of a curved wall, the two sides of the profile shall be parallel (with defined offset) to the wall axis, that is, the wall has a single unchanged thickness.

Figure 118 — Wall body extrusion straight | Figure 119 — Wall body extrusion curved

Clipping Representation Type

The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

- RepresentationIdentifier : 'Body'
- RepresentationType : 'Clipping'

The following constraints apply to the 'Clipping' 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 (or subtypes).

Figure 120 illustrates a clipping for a straight wall using an IfcPolygonalBoundedHalfSpace as SecondOperand in the IfcBooleanClippingResult.

Figure 121 illustrates a clipping for a curved wall using an IfcHalfSpaceSolid as SecondOperand in the IfcBooleanClippingResult.

Figure 120 — Wall body clipping straight | Figure 121 — Wall body clipping curved

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XSD Specification:

<xs:element name="IfcWallStandardCase" type="ifc:IfcWallStandardCase" substitutionGroup="ifc:IfcWall" nillable="true"/>
<xs:complexType name="IfcWallStandardCase">
<xs:complexContent>
<xs:extension base="ifc:IfcWall"/>
</xs:complexContent>
</xs:complexType>

EXPRESS Specification:

ENTITY IfcWallStandardCase

| SUBTYPE OF (IfcWall);

| WHERE

HasMaterialLayerSetUsage | : | 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:

HasMaterialLayerSetUsage | : | A valid instance of IfcWallStandardCase relies on the provision of an IfcMaterialLayerSetUsage.

Inheritance Graph:

ENTITY IfcWallStandardCase

| ENTITY IfcRoot

GlobalId | : | IfcGloballyUniqueId;
OwnerHistory | : | OPTIONAL IfcOwnerHistory;
Name | : | OPTIONAL IfcLabel;
Description | : | OPTIONAL IfcText;

| ENTITY IfcObjectDefinition

| INVERSE

HasAssignments | : | SET OF IfcRelAssigns FOR RelatedObjects;
Nests | : | SET [0:1] OF IfcRelNests FOR RelatedObjects;
IsNestedBy | : | SET OF IfcRelNests FOR RelatingObject;
HasContext | : | SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions;
IsDecomposedBy | : | SET OF IfcRelAggregates FOR RelatingObject;
Decomposes | : | SET [0:1] OF IfcRelAggregates FOR RelatedObjects;
HasAssociations | : | SET OF IfcRelAssociates FOR RelatedObjects;

| ENTITY IfcObject

ObjectType | : | OPTIONAL IfcStrippedOptional;

| INVERSE

IsDeclaredBy | : | SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects;
Declares | : | SET OF IfcRelDefinesByObject FOR RelatingObject;
IsTypedBy | : | SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects;
IsDefinedBy | : | SET OF IfcRelDefinesByProperties FOR RelatedObjects;

| ENTITY IfcProduct

ObjectPlacement | : | OPTIONAL IfcObjectPlacement;
Representation | : | OPTIONAL IfcProductRepresentation;

| INVERSE

ReferencedBy | : | SET OF IfcRelAssignsToProduct FOR RelatingProduct;

| ENTITY IfcElement

Tag | : | OPTIONAL IfcStrippedOptional;

| INVERSE

ConnectedTo | : | SET OF IfcRelConnectsElements FOR RelatingElement;
IsInterferedByElements | : | SET OF IfcRelInterferesElements FOR RelatedElement;
InterferesElements | : | SET OF IfcRelInterferesElements FOR RelatingElement;
HasOpenings | : | SET OF IfcRelVoidsElement FOR RelatingBuildingElement;
ProvidesBoundaries | : | SET OF IfcRelSpaceBoundary FOR RelatedBuildingElement;
ConnectedFrom | : | SET OF IfcRelConnectsElements FOR RelatedElement;
ContainedInStructure | : | SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements;

| ENTITY IfcBuildingElement

| INVERSE

| ENTITY IfcWall

PredefinedType | : | OPTIONAL IfcStrippedOptional;

| ENTITY IfcWallStandardCase

END_ENTITY;

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