IfcStructuralLoadGroup

Definition from IAI: 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. An optional coefficient can be provided to represent safety factors known from several codes of practice. (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.

> HISTORY: New entity in Release IFC2x Edition 2.

Use Definition

The following example illustrates the use of this entity class for the different load group types. Common to all these types is the application of the same grouping mechanism (via IfcGroup) for the specification of the needed groups that may optionally contain an additional load factor (attribute Coefficient). The calculation of internal forces and the provision of safety coefficients is dependent on the building codes used; therefore only a generic representation of load groups is provided by this entity class.

Example for the definition of load cases.
Example for the definition of load combination groups.
Example for the definition of load combinations.

EXPRESS specification:

ENTITY IfcStructuralLoadGroup
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;
END_ENTITY;

Attribute definitions:

PredefinedType | : | Selects a predefined type for the load group. It can be differentiated between load groups, load cases, load combination groups (a necessary construct for the description of load combinations) and load combinations.
ActionType | : | Type of actions in the group. Normally needed if 'PredefinedType' specifies a LOAD_COMBINATION_GROUP.
ActionSource | : | Source of actions in the group. Normally needed if 'PredefinedType' specifies a LOAD_CASE.
Coefficient | : | 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.
Purpose | : | 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.
SourceOfResultGroup | : | Results which were computed using this load group.
LoadGroupFor | : | Analysis models in which this load group is used.

Inheritance graph

ENTITY IfcStructuralLoadGroup;
ENTITY IfcRoot;
GlobalId | : | IfcGloballyUniqueId;
OwnerHistory | : | IfcOwnerHistory;
Name | : | OPTIONAL IfcLabel;
Description | : | OPTIONAL IfcText;
ENTITY IfcObjectDefinition;
INVERSE
HasAssignments | : | SET OF IfcRelAssigns FOR RelatedObjects;
IsDecomposedBy | : | SET OF IfcRelDecomposes FOR RelatingObject;
Decomposes | : | SET [0:1] OF IfcRelDecomposes FOR RelatedObjects;
HasAssociations | : | SET OF IfcRelAssociates FOR RelatedObjects;
ENTITY IfcObject;
ObjectType | : | OPTIONAL IfcLabel;
INVERSE
IsDefinedBy | : | SET OF IfcRelDefines FOR RelatedObjects;
ENTITY IfcGroup;
INVERSE
IsGroupedBy | : | IfcRelAssignsToGroup FOR RelatingGroup;
ENTITY IfcStructuralLoadGroup;
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;
END_ENTITY;