A structural curve action defines an action which is distributed over a curve. A curve action may be connected with a curve member or curve connection, or surface member or surface connection.
HISTORY New entity in IFC4.
{ .change-ifc2x4}
IFC4 CHANGE Former entity IfcStructuralLinearActionVarying from IFC2x2 has been removed and are replaced by this entity.
Coordinate Systems:
See definitions at IfcStructuralActivity.
Topology Use Definitions:
Standard Case: If connected with a curve item, instances of IfcStructuralCurveAction shall not have an ObjectPlacement nor a Representation. It is implied that the placement and representation of the IfcStructuralActivity is the same as the ones of the member or connection.
Special Case 1: If connected with a surface item, instances of IfcStructuralCurveAction shall have an ObjectPlacement and Representation, containing an IfcEdgeCurve. See IfcStructuralActivity for further definitions.
Special Case 2: If not connected with a structural item (which may happen in an incomplete or conceptual model), a curve action should have an ObjectPlacement and Representation, containing an IfcEdgeCurve. See IfcStructuralActivity for further definitions.
Informal Propositions
- If the curve action is of the predefined type CONST, SINUS, or PARABOLA, SELF\IfcStructuralActivity.AppliedLoad must not be of type IfcStructuralLoadConfiguration. In case of SINUS and PARABOLA, the load item defines the maximum of the load at the centre of the load distribution.
- If the curve action is of the predefined type LINEAR, SELF\IfcStructuralActivity.AppliedLoad shall be of type IfcStructuralLoadConfiguration and shall contain two items.
- If the curve action is of the predefined type POLYGONAL, SELF\IfcStructuralActivity.AppliedLoad shall be of type IfcStructuralLoadConfiguration and shall contain three or more items.
- If the curve action is of the predefined type DISCRETE, SELF\IfcStructuralActivity.AppliedLoad shall be of type IfcStructuralLoadConfiguration and shall contain two or more items.
- In case of types LINEAR, POLYGONAL, and DISCRETE, the load items shall have one-dimensional IfcStructuralLoadConfiguration.Locations, defining the location of the load samples in local coordinates of the curve action. The load items shall be provided in ascending order according to their locations. The first and the last load item define the extent of the load distribution.
- Point actions must be of type DISCRETE, thus contain two or more load points. (Single point loads are modeled by IfcStructuralPointAction.)
- All items in SELF\IfcStructuralActivity.AppliedLoad\IfcStructuralLoadConfiguration.Values shall be of the same entity type.
Defines whether load values are given per true length of the curve on which they act, or per length of the projection of the curve in load direction. The latter is only applicable to loads which act in global coordinate directions.
Type of action according to its distribution of load values.
A load can only be related to projected length if it was specified in global coordinate directions (i.e. in analysis model coordinate directions). If a load was specified in local coordinate directions, it can only relate to true length.
The attribute ObjectType shall be given if the predefined type is set to USERDEFINED.
The EQUIDISTANT distribution type is out of scope of structural curve actions.
Linear force and moment along a curve member.
Linear force and moment positioned within a surface member.