IfcStructuralLinearActionVarying

Definition from IAI: Instances of the entity IfcStructuralLinearActionVarying are used to define varying linear actions. IfcStructuralLinearActionVarying inherits the needed attributes and applicable structural load types from its superclass IfcStructuralLinearAction.

> NOTE: This entity definition inherits from its superclass IfcStructuralActivity the mandatory attribute AppliedLoad. It is used as the first list member of the derived list VaryingAppliedLoads

> HISTORY: New entity in Release IFC2x Edition 2.

Topology Use Definition

Instances of IfcStructuralLinearActionVarying shall have a topology representation. It includes a placement and a product representation. The IfcProductRepresentation shall be given by an item of Representations being of type "IfcTopologyRepresentation". The definition of the topological representation is given at the supertype IfcStructuralLinearAction. One additional constraint applies:

- The topology representation has to be given by an IfcEdgeCurve to provide a parameterized geometric representation of the curve between both vertices. This parameterization is needed for the location of the varying loads.

Shape Aspect Use Definition

The attribute VaryingAppliedLoadLocation reference a shape aspect, that has a list of ShapeRepresentations. Each individual IfcShapeRepresentation within that list shall have a single item within its list of Items. The type of the item shall be either:

- IfcCartesianPoint, or
- IfcPointOnCurve

Each list member within the list of ShapeRepresentations corresponds to the list member (at same position) of the list VaryingAppliedLoads, and provides the position of the applied load. At least two applied load values shall be given, the distribution of the applied linear loads across the surface of the planar action is constructed by linear interpolation.

The following examples shows a definition of a varying applied loads by four points on curve.

VaryingAppliedLoads Position | VaryingAppliedLoads Value | VaryingThicknessLocation | Point on curve | Parameter value
[1] identical with AppliedLoad | 8 | IfcShapeAspect. ShapeRepresentations[1] | Items[1] TYPEOF IfcPointOnCurve | 0.
[2] | 8 | IfcShapeAspect. ShapeRepresentations[2] | Items[2] TYPEOF IfcPointOnCurve | 0.35
[3] | 12 | IfcShapeAspect. ShapeRepresentations[3] | Items[3] TYPEOF IfcPointOnCurve | 0.35
[4] | 12 | IfcShapeAspect. ShapeRepresentations[4] | Items[4] TYPEOF IfcPointOnCurve | 0.65
[5] | 0 | IfcShapeAspect.ShapeRepresentations[5] | Items[4] TYPEOF IfcPointOnCurve | 0.85

Example:

Example for the definition of a varying linear action.

EXPRESS specification:

ENTITY IfcStructuralLinearActionVarying
SUBTYPE OF ( | IfcStructuralLinearAction);
VaryingAppliedLoadLocation | : | IfcShapeAspect;
SubsequentAppliedLoads | : | LIST [1:?] OF IfcStructuralLoad;
DERIVE
VaryingAppliedLoads | : | LIST [2:?] OF IfcStructuralLoad := IfcAddToBeginOfList(SELF\IfcStructuralActivity.AppliedLoad, SubsequentAppliedLoads);
END_ENTITY;

Attribute definitions:

VaryingAppliedLoadLocation | : | A shape aspect, containing a list of shape representations, each defining either one Cartesian point or one point on curve (by parameter values) which are needed to provide the positions of the VaryingAppliedLoads. The values contained in the list of IfcShapeAspect.ShapeRepresentations correspond to the values at the same position in the list VaryingAppliedLoads.
SubsequentAppliedLoads | : | A list containing load values which are assigned to the position defined through the shape aspect. The first load is already defined by the inherited attribute AppliedLoad and shall not be contained in this list.
VaryingAppliedLoads | : | Derived list of all varying applied loads by pushing the inherited AppliedLoad value to the beginning of the list of SubsequentAppliedLoads.

Inheritance graph

ENTITY IfcStructuralLinearActionVarying;
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 IfcProduct;
ObjectPlacement | : | OPTIONAL IfcObjectPlacement;
Representation | : | OPTIONAL IfcProductRepresentation;
INVERSE
ReferencedBy | : | SET OF IfcRelAssignsToProduct FOR RelatingProduct;
ENTITY IfcStructuralActivity;
AppliedLoad | : | IfcStructuralLoad;
GlobalOrLocal | : | IfcGlobalOrLocalEnum;
INVERSE
AssignedToStructuralItem | : | IfcRelConnectsStructuralActivity FOR RelatedStructuralActivity;
ENTITY IfcStructuralAction;
DestabilizingLoad | : | BOOLEAN;
CausedBy | : | OPTIONAL IfcStructuralReaction;
ENTITY IfcStructuralLinearAction;
ProjectedOrTrue | : | IfcProjectedOrTrueLengthEnum;
ENTITY IfcStructuralLinearActionVarying;
VaryingAppliedLoadLocation | : | IfcShapeAspect;
SubsequentAppliedLoads | : | LIST [1:?] OF IfcStructuralLoad;
DERIVE
VaryingAppliedLoads | : | LIST [2:?] OF IfcStructuralLoad := IfcAddToBeginOfList(SELF\IfcStructuralActivity.AppliedLoad, SubsequentAppliedLoads);
END_ENTITY;