DEPRECATED
This definition will be removed in a future major release of this standard
6.1.3.42.1 Semantic definition
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 positive 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).
An 'Axis' and a 'Body' shape representation has to be provided, and it is invalid to exchange a 'Tessellation', 'SurfaceModel', 'Brep' or 'MappedRepresentation' representation for the 'Body' shape representation of the IfcWallStandardCase.
Assignment of the information about the current ownership of that object, including owning actor, application, local identification and information captured about the recent changes of the object,
Optional name for use by the participating software systems or users. For some subtypes of IfcRoot the insertion of the Name attribute may be required. This would be enforced by a where rule.
Reference to the relationship objects, that assign (by an association relationship) other subtypes of IfcObject to this object instance. Examples are the association to products, processes, controls, resources or groups.
References to the decomposition relationship being a nesting. It determines that this object definition is a part within an ordered whole/part decomposition relationship. An object occurrence or type can only be part of a single decomposition (to allow hierarchical structures only).
References to the decomposition relationship being a nesting. It determines that this object definition is the whole within an ordered whole/part decomposition relationship. An object or object type can be nested by several other objects (occurrences or types).
References to the context providing context information such as project unit or representation context. It should only be asserted for the uppermost non-spatial object.
References to the decomposition relationship being an aggregation. It determines that this object definition is whole within an unordered whole/part decomposition relationship. An object definition can be aggregated by several other objects (occurrences or parts).
References to the decomposition relationship being an aggregation. It determines that this object definition is a part within an unordered whole/part decomposition relationship. An object definition can only be part of a single decomposition (to allow hierarchical structures only).
Reference to the relationship objects, that associates external references or other resource definitions to the object. Examples are the association to library, documentation or classification.
The type denotes a particular type that indicates the object further. The use has to be established at the level of instantiable subtypes. In particular it holds the user defined type, if the enumeration of the attribute PredefinedType is set to USERDEFINED or when the concrete entity instantiated does not have a PredefinedType attribute. The latter is the case in some exceptional leaf classes and when instantiating IfcBuiltElement directly.
Link to the relationship object pointing to the declaring object that provides the object definitions for this object occurrence. The declaring object has to be part of an object type decomposition. The associated IfcObject, or its subtypes, contains the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes.
Link to the relationship object pointing to the reflected object(s) that receives the object definitions. The reflected object has to be part of an object occurrence decomposition. The associated IfcObject, or its subtypes, provides the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes.
Set of relationships to the object type that provides the type definitions for this object occurrence. The then associated IfcTypeObject, or its subtypes, contains the specific information (or type, or style), that is common to all instances of IfcObject, or its subtypes, referring to the same type.
Set of relationships to property set definitions attached to this object. Those statically or dynamically defined properties contain alphanumeric information content that further defines the object.
This establishes the object coordinate system and placement of the product in space. The placement can either be absolute (relative to the world coordinate system), relative (relative to the object placement of another product), or constrained (e.g. relative to grid axes, or to a linear positioning element). The type of placement is determined by the various subtypes of IfcObjectPlacement. An object placement must be provided if a representation is present.
Reference to the representations of the product, being either a representation (IfcProductRepresentation) or as a special case of a shape representation (IfcProductDefinitionShape). The product definition shape provides for multiple geometric representations of the shape property of the object within the same object coordinate system, defined by the object placement.
Reference to the IfcRelAssignsToProduct relationship, by which other products, processes, controls, resources or actors (as subtypes of IfcObjectDefinition) can be related to this product.
Reference to the objectified relationship IfcRelReferencedInSpatialStructure may be used to relate a product to one or more spatial structure elements in addition to the one in which it is primarily contained.
The tag (or label) identifier at the particular instance of a product, e.g. the serial number, or the position number. It is the identifier at the occurrence level.
Reference to the interference relationship to indicate the element that is interfered. The relationship, if provided, indicates that this element has an interference with one or many other elements.
Reference to the interference relationship to indicate the element that interferes. The relationship, if provided, indicates that this element has an interference with one or many other elements.
Reference to the IfcRelVoidsElement relationship that creates an opening in an element. An element can incorporate zero-to-many openings. For each opening, that voids the element, a new relationship IfcRelVoidsElement is generated.
Reference to the connection relationship with realizing element. The relationship, if provided, assigns this element as the realizing element to the connection, which provides the physical manifestation of the connection relationship.
Containment relationship to the spatial structure element, to which the element is primarily associated. This containment relationship has to be hierarchical, i.e. an element may only be assigned directly to zero or one spatial structure.
Reference to IfcCovering by virtue of the objectified relationship IfcRelCoversBldgElements. It defines the concept of an element having coverings associated.
Reference to the IfcRelAdheresToElement relationship that adheres a IfcSurfaceFeature to an element. An element can incorporate zero-to-many surface features in one relationship.
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Any object occurrence or object type can have a reference to a specific classification reference, i.e. to a particular facet within a classification system.
Any object occurrence can be typed by being assigned to a common object type utilizing this concept. A particular rule, restricting the applicable subtypes of IfcTypeObject that can be assigned, is introduced by overriding this concept at the level of subtypes of IfcObject.
This concept can be applied to the following resources:
An attribute Name and optionally Description can be used for all subypes of IfcObject. For those subtypes, that have an object type definition, such as IfcBeam - IfcBeamType, the common Name and optionally Description is associated with the object type.
Any object occurrence can hold property sets, either directly at the object occurrence as element specific property sets, or at the object type, as type property sets. In this case, the properties that are provided to the object occurrence are the combinations of element specific and type properties. In case that the same property (within the same property set) is defined both in occurrence and type properties, the property value of the occurrence property overrides the property value of the type property.
The body or solid model geometric representation of an IfcProduct is typically defined using a Tessellation or Brep. Subtypes may provide recommendations on other representation types that may be used. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:
The geometric representation of any IfcProduct is provided by the IfcProductDefinitionShape allowing multiple geometric representations. It uses the Product Placement concept utilizing IfcLocalPlacement to establish an object coordinate system, in which all geometric representations are founded.
An IfcElement (so far no further constraints are defined at the level of its subtypes or by view definitions) may be represented as a single or multiple boundary representation models, which include advanced surfaces, usually referred to as NURBS surfaces. The 'AdvancedBrep' representation allows for the representation of complex free-form element shape.
Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a single or multiple Boundary Representation models (which are restricted to be faceted Brep's with or without voids). The Brep representation allows for the representation of complex element shape.
Figure 6.1.3.42.A — Building element body boundary representation
Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a CSG primitive or CSG tree. The CSG representation allows for the representation of complex element shape.
Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a single or multiple surface models, based on either shell or face based surface models. It may also include tessellated models.
Figure 6.1.3.42.B — Element surface model representation
Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a mixed representation, including surface and solid models.
Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a single or multiple tessellated surface models, in particular triangulated surface models.
The 'CoG', Center of Gravity, shape representation is used as a means to verify the correct import by comparing the CoG of the imported geometry with the explicitly provided CoG created during export.
Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented using the 'MappedRepresentation'. This shall be supported as it allows for reusing the geometry definition of a type at all occurrences of the same type. The results are more compact data sets.
The same constraints, as given for 'SurfaceOrSolidModel', 'SurfaceModel', 'Tessellation', 'Brep', and 'AdvancedBrep' geometric representation, shall apply to the IfcRepresentationMap.
Product placement with a Product Linear Placement template. It defines the local coordinate system based on the curve which is referenced by IfcLinearPlacement.RelativePlacement which is an IfcAxis2PlacementLinear.Location using an IfcPointByDistanceExpression.BasisCurve. The local coordinate system is based on the tangent of the curve at Location, its normal in the global Z plane and the cross product of the aforementioned vectors.
The wall axis is represented by a two-dimensional open curve within a particular shape representation. The 'Axis' shape representation is only used to locate the material layer set along the axis, if the IfcMaterialLayerSetUsage is applied to the IfcWall. In this case, the wall axis is used to apply the material layer set usage parameter to the wall geometry.
Axis
IfcPolyline having two Points, or IfcTrimmedCurve with BasisCurve of Type IfcLine for the 'SweptSolid' provided as IfcExtrudedAreaSolid. The axis curve lies on the x/y plane and is parallel to the x-axis of the object coordinate system.
IfcTrimmedCurve with BasisCurve of Type IfcCircle for 'SweptSolid' provided as IfcExtrudedAreaSolid. The axis curve lies on the x/y plane of the object coordinate system, the tangent at the start is along the positive x-axis.
Figure 6.1.3.42.D — Wall axis straight
Figure 6.1.3.42.D 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 6.1.3.42.E — Wall axis curved
Figure 6.1.3.42.E 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.
Extrusion: All extrusion directions shall be supported.
Additional constraints apply to the 'SweptSolid' representation, when an IfcMaterialLayerSetUsage is used:
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 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 6.1.3.42.H 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 6.1.3.42.H — Wall body extrusion straight
Figure 6.1.3.42.I 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.
A wall may decomposed into parts such as framing and panels on each side. For efficiency, each part may reuse geometry using the mapped geometry concept.
Figure 6.1.3.42.J — A wall decomposed into parts.
This concept can be applied to the following resources:
As shown in Figure 6.1.3.42.K, openings within the composite wall are directly assigned to IfcWall using IfcRelVoidsElement pointing to IfcOpeningElement and apply to all aggregated parts. If individual parts have cutting and other voiding features, then the decomposed parts have a separate voiding relationship IfcRelVoidsElement pointing to IfcVoidingFeature.
Figure 6.1.3.42.K — How individual parts being cut may be expressed.
The IfcMaterialLayerSetUsage.OffsetFromReferenceLine is the distance parallel to the reference axis and always within the base
(XY) plane of the reference coordinate system. A positive 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 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.
Axis
IfcPolyline having two Points, or
IfcTrimmedCurve with BasisCurve of TypeIfcLine for the 'SweptSolid' provided as
IfcExtrudedAreaSolid. The axis curve lies on the x/y plane and is parallel to the x-axis of
the object coordinate system.
IfcTrimmedCurve with BasisCurve of TypeIfcCircle for 'SweptSolid' provided as
IfcExtrudedAreaSolid. The axis curve lies on the x/y plane
of the object coordinate system, the tangent at the start is along
the positive x-axis.
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 6.1.3.42.Q 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 6.1.3.42.R 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 6.1.3.42.Q — Wall body extrusion straightFigure 6.1.3.42.R — Wall body extrusion curved
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.
Figure 6.1.3.42.T 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 the distance parallel to the reference axis and always within the base
(XY) plane of the reference coordinate system. A positive 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.
