A structural action is a structural activity that acts upon a structural item or building element. Structural actions are grouped into either an IfcStructuralLoadGroup of predefined type LOAD_GROUP or, more often, an IfcStructuralLoadCase. This is accomplished via the inverse relationship HasAssignments and an IfcRelAssignsToGroup relationship object. IfcStructuralLoadGroup.LoadGroupFor or IfcStructuralLoadCase.LoadGroupFor respectively refers to the structural analysis model(s) in which the loads are used. 

It is possible to establish relationships between actions in one analysis model and reactions in another analysis model which cause the actions. For example, a support reaction from one structural system can be taken over as a load onto another supporting structural system. This is expressed by means of the inverse relationship ReferencedBy of the action and an IfcRelAssignsToProduct relationship object. IfcRelAssignsToProduct.Name is set to 'Causes' and IfcRelAssignsToProduct.RelatedObjects refers to an instance of a subtype of IfcStructuralReaction.