Example for the definition of a varying linear action.
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:
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:
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:
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Example for the definition of a varying linear action. |
EXPRESS specification:
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| 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. |
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