IfcStructuralLoadGroup

Natural language names
deLastgruppe / Lastkombination
enStructural Load Group
Change log
ItemSPFXMLChangeDescription
IFC2x3 to IFC4
    IfcStructuralLoadGroup
      OwnerHistoryMODIFIEDInstantiation changed to OPTIONAL.
Semantic definitions at the entity
Entity definition

The entity IfcStructuralLoadGroup is used to structure the physical impacts. By using the grouping features inherited from IfcGroup, instances of IfcStructuralAction (or its subclasses) and of IfcStructuralLoadGroup can be used to define load groups, load cases and load combinations. (See also IfcLoadGroupTypeEnum.)

NOTE  Important functionality for the description of a load-bearing system is derived from the existing IFC entity IfcGroup. This class provides, via the relationship class IfcRelAssignsToGroup, the needed grouping mechanism. In this way, instances of IfcStructuralAction belonging to a specific load group can be unambiguously determined.
NOTE  The relationship class IfcRelAssignsToGroupByFactor is used to group load cases into load combinations. The factor provided in this assignment relationship is to applied together with the optional IfcStructuralLoadGroup.Coefficient. Unlike this coefficient which always affects the load group, the IfcRelAssignsToGroupByFactor.Factor is specific for a load case—load combination pair. As many instances of IfcRelAssignsToGroupByFactor are used within one load combination as there are different Factors to be applied to load cases in the load combination. On the other hand, a load case may appear in more than one load combination and can have a different Factor in each assignment by IfcRelAssignsToGroupByFactor.
HISTORY  New entity in IFC2x2.
IFC4 CHANGE  Subtype IfcStructuralLoadCase added. Informal propositions and WHERE rule added. Predefined type LOAD_COMBINATION_GROUP made obsolete and removed.

Informal Propositions:

  1. Load groups of type LOAD_GROUP shall only contain instances of IfcStructuralAction.
  2. Load groups of type LOAD_CASE shall always be instantiated from the subtype IfcStructuralLoadCase, not directly from the generic type IfcStructuralLoadGroup itself.
  3. Instances of IfcStructuralLoadCase shall only contain instances of IfcStructuralAction or/ and instances of IfcStructuralLoadGroup of type LOAD_GROUP.
  4. Load groups of type LOAD_COMBINATION shall only contain instances of IfcStructuralLoadCase.
Attribute definitions
#AttributeTypeCardinalityDescription C
6PredefinedTypeIfcLoadGroupTypeEnum[1:1] Selects a predefined type for the load group. It can be differentiated between load groups, load cases, load combinations, or userdefined grouping levels. X
7ActionTypeIfcActionTypeEnum[1:1] Type of actions in the group. Normally needed if 'PredefinedType' specifies a LOAD_CASE.X
8ActionSourceIfcActionSourceTypeEnum[1:1] Source of actions in the group. Normally needed if 'PredefinedType' specifies a LOAD_CASE.X
9CoefficientIfcRatioMeasure[0:1] Load factor. If omitted, a factor is not yet known or not specified. A load factor of 1.0 shall be explicitly exported as Coefficient = 1.0.X
10PurposeIfcLabel[0:1] Description of the purpose of this instance. Among else, possible values of the Purpose of load combinations are 'SLS', 'ULS', 'ALS' to indicate serviceability, ultimate, or accidental limit state.X
SourceOfResultGroupIfcStructuralResultGroup
@ResultForLoadGroup		S[0:1]Results which were computed using this load group.X
LoadGroupForIfcStructuralAnalysisModel
@LoadedBy		S[0:?]Analysis models in which this load group is used.X
Formal Propositions
RuleDescription
HasObjectTypeThe attribute ObjectType shall be given if the predefined type, action type, or action source is set to USERDEFINED.
Inherited definitions from supertypes
Entity inheritance IfcStructuralLoadCase IfcGroup IfcObject IfcObjectDefinition IfcRoot
Attribute inheritance
#AttributeTypeCardinalityDescriptionC
IfcRoot
1GlobalIdIfcGloballyUniqueId[1:1] Assignment of a globally unique identifier within the entire software world. X
2OwnerHistoryIfcOwnerHistory[0:1] 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,
NOTE  only the last modification in stored - either as addition, deletion or modification.
X
3NameIfcLabel[0:1] 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. X
4DescriptionIfcText[0:1] Optional description, provided for exchanging informative comments.X
IfcObjectDefinition
HasAssignmentsIfcRelAssigns
@RelatedObjects		S[0:?]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.X
NestsIfcRelNests
@RelatedObjects		S[0:1]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 strutures only). X
IsNestedByIfcRelNests
@RelatingObject		S[0:?]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). X
HasContextIfcRelDeclares
@RelatedDefinitions		S[0:1]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. X
IsDecomposedByIfcRelAggregates
@RelatingObject		S[0:?]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 definitions can be aggregated by several other objects (occurrences or parts). X
DecomposesIfcRelAggregates
@RelatedObjects		S[0:1]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 definitions can only be part of a single decomposition (to allow hierarchical strutures only). X
HasAssociationsIfcRelAssociates
@RelatedObjects		S[0:?]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.X
IfcObject
5ObjectTypeIfcLabel[0:1] 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.
X
IsDeclaredByIfcRelDefinesByObject
@RelatedObjects		S[0:1]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. X
DeclaresIfcRelDefinesByObject
@RelatingObject		S[0:?]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. X
IsTypedByIfcRelDefinesByType
@RelatedObjects		S[0:1]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. X
IsDefinedByIfcRelDefinesByProperties
@RelatedObjects		S[0:?]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. X
IfcGroup
IsGroupedByIfcRelAssignsToGroup
@RelatingGroup		S[0:?]Reference to the relationship IfcRelAssignsToGroup that assigns the one to many group members to the IfcGroup object. X
IfcStructuralLoadGroup
6PredefinedTypeIfcLoadGroupTypeEnum[1:1] Selects a predefined type for the load group. It can be differentiated between load groups, load cases, load combinations, or userdefined grouping levels. X
7ActionTypeIfcActionTypeEnum[1:1] Type of actions in the group. Normally needed if 'PredefinedType' specifies a LOAD_CASE.X
8ActionSourceIfcActionSourceTypeEnum[1:1] Source of actions in the group. Normally needed if 'PredefinedType' specifies a LOAD_CASE.X
9CoefficientIfcRatioMeasure[0:1] Load factor. If omitted, a factor is not yet known or not specified. A load factor of 1.0 shall be explicitly exported as Coefficient = 1.0.X
10PurposeIfcLabel[0:1] Description of the purpose of this instance. Among else, possible values of the Purpose of load combinations are 'SLS', 'ULS', 'ALS' to indicate serviceability, ultimate, or accidental limit state.X
SourceOfResultGroupIfcStructuralResultGroup
@ResultForLoadGroup		S[0:1]Results which were computed using this load group.X
LoadGroupForIfcStructuralAnalysisModel
@LoadedBy		S[0:?]Analysis models in which this load group is used.X
Definitions applying to Common Use Definitions

 Instance diagram

Concept usage

Group Assignment

The Group Assignment concept applies to this entity as shown in Table 632.

RelatedTypeDescription
Structural load cases applicable to the load group.

Table 632 — IfcStructuralLoadGroup Group Assignment



Concept inheritance

#ConceptModel View
IfcRoot
Software IdentityCommon Use Definitions
Revision ControlCommon Use Definitions
IfcObject
Object Occurrence Predefined TypeCommon Use Definitions
IfcGroup
IfcStructuralLoadGroup
Group AssignmentCommon Use Definitions
Examples
Formal representations
XSD Specification
 <xs:element name="IfcStructuralLoadGroup" type="ifc:IfcStructuralLoadGroup" substitutionGroup="ifc:IfcGroup" nillable="true"/>
 <xs:complexType name="IfcStructuralLoadGroup">
  <xs:complexContent>
   <xs:extension base="ifc:IfcGroup">
    <xs:attribute name="PredefinedType" type="ifc:IfcLoadGroupTypeEnum" use="optional"/>
    <xs:attribute name="ActionType" type="ifc:IfcActionTypeEnum" use="optional"/>
    <xs:attribute name="ActionSource" type="ifc:IfcActionSourceTypeEnum" use="optional"/>
    <xs:attribute name="Coefficient" type="ifc:IfcRatioMeasure" use="optional"/>
    <xs:attribute name="Purpose" type="ifc:IfcLabel" use="optional"/>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>
EXPRESS Specification
ENTITY IfcStructuralLoadGroup
 SUPERTYPE OF(IfcStructuralLoadCase)
 SUBTYPE OF (IfcGroup);
  PredefinedType : IfcLoadGroupTypeEnum;
  ActionType : IfcActionTypeEnum;
  ActionSource : IfcActionSourceTypeEnum;
  Coefficient : OPTIONAL IfcRatioMeasure;
  Purpose : OPTIONAL IfcLabel;
 INVERSE
  SourceOfResultGroup : SET [0:1] OF IfcStructuralResultGroup FOR ResultForLoadGroup;
  LoadGroupFor : SET OF IfcStructuralAnalysisModel FOR LoadedBy;
 WHERE
  HasObjectType : ( (PredefinedType <> IfcLoadGroupTypeEnum.USERDEFINED) AND (ActionType <> IfcActionTypeEnum.USERDEFINED) AND (ActionSource <> IfcActionSourceTypeEnum.USERDEFINED) ) OR EXISTS(SELF\IfcObject.ObjectType);
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

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