A load case is a load group, commonly used to group loads from the same action source.

HISTORY  New entity in IFC4.

Common Use Definitions

The following concepts are inherited at supertypes:

 Instance diagram

Group Assignment

The Group Assignment concept applies to this entity as shown in Table 631.
IfcStructuralActionStructural actions for the load case.
IfcStructuralLoadCaseStructural load cases applicable to the load group.

Table 631 — IfcStructuralLoadCase Group Assignment

XSD Specification:

 <xs:element name="IfcStructuralLoadCase" type="ifc:IfcStructuralLoadCase" substitutionGroup="ifc:IfcStructuralLoadGroup" nillable="true"/>
 <xs:complexType name="IfcStructuralLoadCase">
   <xs:extension base="ifc:IfcStructuralLoadGroup">
    <xs:attribute name="SelfWeightCoefficients" use="optional">
        <xs:list itemType="ifc:IfcRatioMeasure"/>
       <xs:minLength value="3"/>
       <xs:maxLength value="3"/>

EXPRESS Specification:

ENTITY IfcStructuralLoadCase
SUBTYPE OF IfcStructuralLoadGroup;
SelfWeightCoefficients : OPTIONAL LIST [3:3] OF IfcRatioMeasure;
IsLoadCasePredefinedType : SELF\IfcStructuralLoadGroup.PredefinedType = IfcLoadGroupTypeEnum.LOAD_CASE;

Link to EXPRESS-G diagram EXPRESS-G diagram

Attribute Definitions:

SelfWeightCoefficients : The self weight coefficients specify ratios at which loads due to weight of members shall be included in the load case. These loads are not explicitly modeled as instances of IfcStructuralAction. Instead they shall be calculated according to geometry, section, and material of each member.

The three components of the self weight vector correspond with the x,y,z directions of the so-called global coordinates, i.e. the directions of the shared ObjectPlacement of all items in an IfcStructuralAnalysisModel. For example, if the object placement defines a z axis which is upright like the IfcProject's world coordinate system, then the self weight coefficients would typically be [0.,0.,-1.] in a load case of dead loads with self weight.

The overall coefficient in the inherited attribute Coefficient shall not be applied to SelfWeightCoefficients of the same instance of IfcStructuralLoadCase. It only applies to actions and load groups which are grouped below the load case, not to the load case's computed self weight.

Formal Propositions:

IsLoadCasePredefinedType : An instance of this subtype of structural load group cannot be of any other type than that of a load case.

Inheritance Graph:

ENTITY IfcStructuralLoadCase
GlobalId : IfcGloballyUniqueId;
OwnerHistory : OPTIONAL IfcOwnerHistory;
Name : OPTIONAL IfcLabel;
Description : OPTIONAL IfcText;
ENTITY IfcObjectDefinition
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 IfcLabel;
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;
IsGroupedBy : SET OF IfcRelAssignsToGroup FOR RelatingGroup;
ENTITY IfcStructuralLoadGroup
PredefinedType : IfcLoadGroupTypeEnum;
ActionType : IfcActionTypeEnum;
ActionSource : IfcActionSourceTypeEnum;
Coefficient : OPTIONAL IfcRatioMeasure;
Purpose : OPTIONAL IfcLabel;
SourceOfResultGroup : SET [0:1] OF IfcStructuralResultGroup FOR ResultForLoadGroup;
LoadGroupFor : SET OF IfcStructuralAnalysisModel FOR LoadedBy;
ENTITY IfcStructuralLoadCase
SelfWeightCoefficients : OPTIONAL LIST [3:3] OF IfcRatioMeasure;

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