SEM Family Name & ID

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SEM -04 Primary Building Elements

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1-Header

IFC Release: 2.3.TC1

SEM Member Names & ID

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04-01Beam, 04-02BuildingElementProxy, 04-03 Column, Covering, 04-04CurtainWall, 04-05Member, 04-06Pile, Plate, 04-07 Ramp, RampFlight, Railing, 04-08Roof, 04-09 Slab, 04-10Stair, StairFlight, 04-11Wall, BuildingElementComponent, Window, 04-12 BuildingElementAssembly, 04-13 BuildingTransportElement(some greyed out items moved to BuildingComponent, others to be implemented later.)

Organization: Pankow Foundation, PCI

Creation date: 14/5/2011

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Author(s): ): Chuck Eastman

Revision History: 10/6/2011 C Eastman

SEM Description:

IfcBuildingElement is a supertypeclass for a set of individual primary building elements. The full set of subtypes is listed below. Some of these are top level elements, that are placed in the Spatial Configuration Hierarchy, while others are components of other Building Elements. We denote Primary Building Elements to be those that are normally directly placed within the spatial configuration hierarchy above the IfcSpace level. This set of Primary Building Elements are represented as a SEM family and have similar syntactic structure. They are also primary building elements. We also place IfcTransportElement in the same class, as it meets the same qualifications.
Primary Building Elements may provide the core definition of the piece or reference a Building Element Type that carries a shared object definition (see Building Element Type). The Release 2x3 IfcBuildingElement sub-types that are primary are IfcBeam, IfcBuildingElementProxy,IfcColumn, IfcCovering,IfcCurtainWall, IfcDoor,IfcFooting, IfcMember, IfcPile, IfcPlate, IfcRailing, IfcRamp, IfcRampFlight, IfcRoof, IfcSlab, IfcStair, IfcStairFlight, IfcWall, IfcBuildingElementComponent, IfcWindow, IfcBuildingElementAssembly, with the non-primary elements crossed out, and that will be treated separately. If the appropriate subtype of IfcBuildingElementType is attached using the IfcRelDefinedByType.RelatingType objectified relationship and is accessible by the inverse IsDefinedBy attribute, then portion or all of the definition is provided by the Type.
Primary Building Elements may be defined as individuals and typically carry a set of: location, shape, and other properties that provide the semantics of the element. The Primary Building Elements and any special conditions of the type are listed below.

SEM Family Name

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SEM -04 Primary Building Elements

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2-Relations

Identify SEMs Outside this Family that itLinks With

List of Parent SEMs, if any:
Spatial Configuration / IfcProject, IfcSite, IfcBuilding, IfcBuildingStorey, IfcSpace
Building ElementTypes / IfcBuildingElementProxyType, IfcCoveringType, IfcBeamType, IfcColumnType, IfcCurtainWallType, IfcDoorType, IfcMemberType, IfcRailingType, IfcRampType, IfcRampFlightType, IfcWallType,IfcSlabType, IfcStairFlightType, IfcWindowType, IfcStairType, IfcRoofType, IfcPileType, IfcFootingType, IfcBuildingElementComponentType, IfcPlateType
Elements that will not directly reference the spatial hierarchy are removed from this category.
IfcGrid / IfcGrid
List of Child SEMs, if any:
(Many relation objects may be applied to BuildingElements) / IfcRelAggregates,IfnRelAssigns,IfcRelAssociates, IfcRelCovers, IfcRelDecomposes,IfcRelDefines,IfcRelFillsElement,IfcRelNests, IfcRelProjectsElement,IfcRelSpaceBoundary,IfcRelVoidElement

SEM Family Name

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SEM -04 Primary Building Elements

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3-Linages

SEM Precedent Sequence <Identifies all the sequences where this SEM may be applied, with both before and after links to other SEMS its execution, and which Member(s) to use This may be a large table

Scenario (Business purpose) SEMs Used
  1. Assign BuildingElement subtype to Spatial Configuration hierarchy, to Site, Building or BuildingStory
SEM-(01-04) SEM- 04-(01-13)
  1. Assign BuildingElement subtype to BuildingElementType, if defined this way
SEM-(02-11) SEM- 04-(01-13)
  1. Link BuildingElement subtype to IfcGrid, if localPlacement is defined this way
SEM-(02-11) SEM- 04-(01-13)

SEM Member Name

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SEMS: 04-BeamType-01, 04-ColumnType-03, 04-SlabType-09,

04-12 BuildingElementAssembly

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IFC Binding for Each Member SEM

Version History

/ 14/5/2011 C Eastman

SEM Member binding diagram binding diagram using flattened entity shapes, for the general case of SEM family; list in title the cases, if any, that this applies to without elaboration



The above Objectified Relationship is optionally used if the BuildingElement is partially defined by a BuildingElementType.
SEM Description:
Primary Building Element have many relations to deal with its relative placement spatially, its properties, embeds, connections, components and other relations. These are handled using the INVERSE relations. Those potentially relevant are:
  1. Grouping - being part of a logical group of objects (erection sequences, supply source,)
IfcGroup has subtypes including IfcSystem, IfcZone, IfcStructuralLoadGroup. Groups may be defined recursively.
  • objectified relationship: IfcRelAssignsToGroup
  • inverse attribute: HasAssignment
  1. Work processes - reference to work tasks, in which this building element is used; should be used to 4D simulation of linking objects with process.
  2. objectified relationship: IfcRelAssignsToProcess
  3. inverse attribute: HasAssignments
  4. Aggregation - aggregated together with other elements to form an aggregate. Examples include a oof with components, precast piece with beams aggregated itno slab, a steel truss
  5. objectified relationship: IfcRelAggregates
  6. inverse attribute (for container): IsDecomposedBy
  7. inverse attribute (for contained parts): Decomposes
  8. Material - assignment of material used by this building element. It is one of the SELECT type IfcMateriaslSelect: IfcMaterial, IfcMaterialList, IfcMaterialLayer., IfcMaterialLayerSet, IfcMaterialLayerSetUsage,
  9. objectified relationship: IfcRelAssociatesMaterial
  10. inverse attribute: HasAssociations
  11. Classification - assigned reference to an external classification
  12. objectified relationship: IfcRelAssociatesClassification
  13. inverse attribute: HasAssociations
  14. Documentation - assigned reference to an external documentation (steel sections, pipe spec)
  15. objectified relationship: IfcRelAssociatesDocumentation
  16. inverse attribute: HasAssociations
  17. Type - reference to the common product type information for the element occurrence; this inverse relation indicates that the instance is defined by a BuildingElementType
  18. objectified relationship: IfcRelDefinesByType
  19. inverse attribute: IsDefinedBy
  20. Connection - connectivity to other elements, including the definition of the joint. Relies on IfcRelConnectsElements and has as subtypes: IfcRelConnectsWithRealizingElements, IfcRelConnectsPathElements (for IfcWall elements).
  • objectified relationship: IfcRelConnectsElements
  • inverse attribute: ConnectedTo
  • inverse attribute: ConnectedFrom
  1. Properties - reference to all attached properties, including quantities
  2. objectified relationship: IfcRelDefinesByProperties
  3. inverse attribute: IsDefinedBy
  4. Realization - information, whether the building element is used to realize a connection (e.g. as a weld in a connection between two members). Used with IfcConnection.
  5. objectified relationship: IfcRelConnectsWithRealizingElements
  6. inverse attribute: IsConnectionRealization
  7. Assignment to spatial structure - hierarchical assignment to the right level within the spatial structure. Is required for all primary spatial objects; objects that are components of a Primary Building Element have the same spatial structure as its aggregated element.
  8. objectified relationship: IfcRelContainedInSpatialStructure
  9. inverse attribute: ContainedInStructure
  10. Reference to spatial structure(s) - non hierarchical reference to one or more elements within the spatial structure (e.g. a curtain wall, being contained in the building, references several stories)
  11. objectified relationship: IfcRelContainedInSpatialStructure
  12. inverse attribute: ContainedInStructure
  13. Boundary - provision of space boundaries by this building element. Applies to Building Element relations with Space objects, for different uses.
  14. objectified relationship: IfcRelSpaceBoundary
  15. inverse attribute: ProvidesBoundaries
  16. Coverings - assignment of covering elements to this building element Covering may be assigned to Building Elements or to Spaces (assigning the same covering to both Building Element and Space will result in quantity errors. (note: for interior finishes, covering elements are assigned to the space,for fabricated elements (steel, concrete) covering elements are assigned to Building Element.
  17. objectified relationship: IfcRelCoversBldgElements
  18. inverse attribute: HasCoverings
Spaces are covered with IfcRelCoversSpaces.
  • objectified relationship: IfcRelCoversSpaces
  • inverse attribute: HasCoverings
  1. Voids –defines any openings, recesses or other voids subtracted from the Building Element geometry
  2. objectified relationship: IfcRelVoidsElement
  3. inverse attribute: HasOpenings
  4. Projection - information, whether the building element has projections (such as a fascia, cast-in-place sill)
  5. objectified relationship: IfcRelProjectsElement
  6. inverse attribute: HasProjections
  7. Structural member reference - information whether the building element is represented in a structural analysis model by a structural member; required to be a one-to-one relationship
  8. objectified relationship: IfcRelConnectsStructuralElement
  9. inverse attribute: HasStructuralMember
These relations provide the semantic extensions needed for Building Elements and are described in their variou uses.
In the case where there is no associated type, the full definition of a building element is defined with the element. If it references a type, then the definition is split (in various ways) between them.
Each Element has a local placement, usually within the spatial containment hierarchy using IfcReferencedInSpatialStructure.

SEM Member Methods <Identifies the Methods needed to insert a Member of this SEM Family into the existing SEM structure. Some may be optional, other always apply

  1. Create Building Element instance.
  2. Assign placement within Spatial Containment Hierarchy
  3. Assign the appropriate BuildingElementType, if this is used.
  4. Assign the local placement, either to the Spatial Containment hierarchy or with reference to a Grid reference point (for Grids, see SEM-03-02.)

SEM Family Name

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SEM -04 Primary Building Elements

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Concepts used to define this SEM<list of the Concepts from IFC Solutions Factory that are being re-placed or re-used in the current SEM Family>

PCI-053 Element Attributes
PCI-062 Precast Piece Containment
PCI-063 Relative Placement
VBL-170 GUID (also MVC-848)
VBL-171 Name (also MVC-849)
VBL-172 Description (also MVC-850)

Concepts are available from IFC Solutions Factory Website