IfcMember
Definition from IAI: An IfcMember is a structural member designed to carry loads between or beyond points of support. It is not required to be load bearing. The location of the member (being horizontal, vertical or sloped) is not relevant to its definition (in contrary to IfcBeam and IfcColumn).
The material of the IfcMember is defined by the IfcMaterial and attached by the IfcRelAssociatesMaterial. It is accessible by the inverse HasAssociations relationship.
A particular usage type for the IfcMember can be given by refering to the type object IfcMemberType, using the IfcRelDefinesByType relationship, or (if only occurrence information is given) by using the ObjectType attribute. Recommended values are 'member' (the default), 'brace', 'collar', 'member', 'post', 'purlin', 'rafter', 'stringer', 'strut'.
HISTORY New entity in IFC Release 2x2 Addendum.
IFC2x Edition 2 Addendum CHANGE The entity IfcMember has been added. Upward compatibility for file based exchange is guaranteed.
Property Set Use Definition
The property sets relating to the IfcMember are defined by the IfcPropertySet and attached by the IfcRelDefinesByProperties relationship. It is accessible by the inverse IsDefinedBy relationship. The following property set definitions specific to the IfcMember are part of this IFC release:
Quantity Use Definition
The quantities relating to the IfcMember are defined by the IfcElementQuantity and attached by the IfcRelDefinesByProperties relationship. It is accessible by the inverse IsDefinedBy relationship. The following quantities are foreseen, but will be subjected to the local standard of measurement used:
| Name | Description | Value Type |
| NominalLength | Total nominal length of the member, not taking into account any cut-out's or other processing features. | IfcQuantityLength |
| CrossSectionArea | Total area of the cross section (or profile) of the member. The exact definition and calculation rules depend on the method of measurement used. | IfcQuantityArea |
| OuterSurfaceArea | Total area of the extruded surfaces of the member (not taking into account the end cap areas), normally generated as perimeter * length. | IfcQuantityArea |
| TotalSurfaceArea | Total area of the member, normally generated as perimeter * length + 2 * cross section area. | IfcQuantityArea |
| GrossVolume | Total gross volume of the member, not taking into account possible processing features (cut-out's, etc.) or openings and recesses. The exact definition and calculation rules depend on the method of measurement used. | IfcQuantityVolume |
| NetVolume | Total net volume of the member, taking into account possible processing features (cut-out's, etc.) or openings and recesses. The exact definition and calculation rules depend on the method of measurement used. | IfcQuantityVolume |
| GrossWeight | Total gross weight of the member without add-on parts, not taking into account possible processing features (cut-out's, etc.) or openings and recesses. | IfcQuantityWeight |
| NetWeight | Total net weight of the member without add-on parts, taking into account possible processing features (cut-out's, etc.) or openings and recesses. | IfcQuantityWeight |
Containment Use Definitions
The IfcMember, as any subtype of IfcBuildingElement, may participate in two different containment relationships. The first (and in most implementation scenarios mandatory) relationship is the hierachical spatial containment, the second (optional) relationship is the aggregation within an element assembly.
Geometry Use Definitions
The geometric representation of IfcMember is given by the IfcProductDefinitionShape, allowing multiple geometric representations. Included are:
Local Placement
The local placement for IfcMember is defined in its supertype IfcProduct. It is defined by the IfcLocalPlacement, which defines the local coordinate system that is referenced by all geometric representations.
Geometric Representations
Currently, the use of 'SweptSolid', 'Clipping', 'Brep' and 'MappedRepresentation' representations is supported. In addition the general representation types 'SurfaceModel' and 'BoundingBox' are allowed. The geometry use definition for 'BoundingBox', 'SurfaceModel' and 'Brep' is explained at IfcBuildingElement.
SweptSolid Representation
The standard geometric representation of IfcMember is defined using the 'SweptSolid' representation. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:
The following additional constraints apply to the 'SweptSolid' representation:
EXAMPLE: standard geometric representation.
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The following interpretation of dimension parameter applies for circular members: |
Advanced SweptSolid and Clipping Representation
The advanced geometric representation of IfcMember is defined using the 'SweptSolid' (enhanced by additional profile types) or 'Clipping' geometry. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:
The following constraints apply to the advanced representation:
EXAMPLE advanced geometric representation
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Use of non-perpendicular extrusion to create the IfcExtrudedAreaSolid. |
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Use of IfcBooleanClippingResult between an IfcExtrudedAreaSolid and an IfcHalfSpaceSolid to create a clipped body. |
MappedRepresentation
In addition to the standard and advanced geometric representation of IfcMember that is defined using the 'SweptSolid' or 'Clipping' geometry, also the 'MappedRepresentation' shall be supported as it allows for reusing the geometry definition of the member type at all occurrences of the same type. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:
The same constraints, as given for the standard 'SweptSolid' and the advanced 'SweptSolid' and 'Clipping' geometric representation, shall apply to the MappedRepresentation of the IfcRepresentationMap.
EXPRESS specification:
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