This entity defines a reaction which occurs distributed over a surface. A surface reaction may be connected with a surface member or surface connection.
If the surface reaction is of the predefined type BILINEAR, SELF\IfcStructuralActivity.AppliedLoad shall be of type IfcStructuralLoadConfiguration and shall contain three items with two-dimensional IfcStructuralLoadConfiguration.Locations, defining the location of the result samples in local coordinates of the surface reaction.
If the surface reaction is of the predefined type DISCRETE, SELF\IfcStructuralActivity.AppliedLoad shall be of type IfcStructuralLoadConfiguration and shall contain two or more items with two-dimensional locations.
If the surface reaction is of the predefined type ISOCONTOUR, SELF\IfcStructuralActivity.AppliedLoad shall be of type IfcStructuralLoadConfiguration and shall contain the same number of items as the set SELF.IfcProduct.Representation.Representations[?].Items. Each item in the load configuration shall have a two-dimensional location, defining the location of the result samples in local coordinates of the surface reaction. Each item in SELF\IfcStructuralActivity.AppliedLoad shall be located at exactly one of the isocontours.
NOTE The set of representation items is unordered, hence result locations are required to correlate result values and isocontours.
NOTE Isocontours are represented as IfcPcurves which are defined in terms of surface parameters u,v, while result locations are given in local surface item coordinates x,y. It is strongly recommended that the surface parameterization u,v is scaled 1:1 in order to avoid different scales of u,v versus x,y. If u,v are scaled 1:1 and the IfcPcurve's base surface is identical with the surface item's base surface, u,v and local x,y are identical.
Assignment of the information about the current ownership of that object, including owning actor, application, local identification and information captured about the recent changes of the object,
Optional name for use by the participating software systems or users. For some subtypes of IfcRoot the insertion of the Name attribute may be required. This would be enforced by a where rule.
Reference to the relationship objects, that assign (by an association relationship) other subtypes of IfcObject to this object instance. Examples are the association to products, processes, controls, resources or groups.
References to the decomposition relationship being a nesting. It determines that this object definition is a part within an ordered whole/part decomposition relationship. An object occurrence or type can only be part of a single decomposition (to allow hierarchical structures only).
References to the decomposition relationship being a nesting. It determines that this object definition is the whole within an ordered whole/part decomposition relationship. An object or object type can be nested by several other objects (occurrences or types).
References to the context providing context information such as project unit or representation context. It should only be asserted for the uppermost non-spatial object.
References to the decomposition relationship being an aggregation. It determines that this object definition is whole within an unordered whole/part decomposition relationship. An object definition can be aggregated by several other objects (occurrences or parts).
References to the decomposition relationship being an aggregation. It determines that this object definition is a part within an unordered whole/part decomposition relationship. An object definition can only be part of a single decomposition (to allow hierarchical structures only).
Reference to the relationship objects, that associates external references or other resource definitions to the object. Examples are the association to library, documentation or classification.
The type denotes a particular type that indicates the object further. The use has to be established at the level of instantiable subtypes. In particular it holds the user defined type, if the enumeration of the attribute PredefinedType is set to USERDEFINED or when the concrete entity instantiated does not have a PredefinedType attribute. The latter is the case in some exceptional leaf classes and when instantiating IfcBuiltElement directly.
Link to the relationship object pointing to the declaring object that provides the object definitions for this object occurrence. The declaring object has to be part of an object type decomposition. The associated IfcObject, or its subtypes, contains the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes.
Link to the relationship object pointing to the reflected object(s) that receives the object definitions. The reflected object has to be part of an object occurrence decomposition. The associated IfcObject, or its subtypes, provides the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes.
Set of relationships to the object type that provides the type definitions for this object occurrence. The then associated IfcTypeObject, or its subtypes, contains the specific information (or type, or style), that is common to all instances of IfcObject, or its subtypes, referring to the same type.
Set of relationships to property set definitions attached to this object. Those statically or dynamically defined properties contain alphanumeric information content that further defines the object.
This establishes the object coordinate system and placement of the product in space. The placement can either be absolute (relative to the world coordinate system), relative (relative to the object placement of another product), or constrained (e.g. relative to grid axes, or to a linear positioning element). The type of placement is determined by the various subtypes of IfcObjectPlacement. An object placement must be provided if a representation is present.
Reference to the representations of the product, being either a representation (IfcProductRepresentation) or as a special case of a shape representation (IfcProductDefinitionShape). The product definition shape provides for multiple geometric representations of the shape property of the object within the same object coordinate system, defined by the object placement.
Reference to the IfcRelAssignsToProduct relationship, by which other products, processes, controls, resources or actors (as subtypes of IfcObjectDefinition) can be related to this product.
Reference to the objectified relationship IfcRelReferencedInSpatialStructure may be used to relate a product to one or more spatial structure elements in addition to the one in which it is primarily contained.
Load or result resource object which defines the load type, direction, and load values.
In case of activities which are variably distributed over curves or surfaces, IfcStructuralLoadConfiguration is used which provides a list of load samples and their locations within the load distribution, measured in local coordinates of the curve or surface on which this activity acts. The contents of this load or result distribution may be further restricted by definitions at subtypes of IfcStructuralActivity.
Indicates whether the load directions refer to the global coordinate system (global to
the analysis model, i.e. as established by IfcStructuralAnalysisModel.SharedPlacement)
or to the local coordinate system (local to the activity or connected item, as established by
an explicit or implied representation and its parameter space).
Any object occurrence or object type can have a reference to a specific classification reference, i.e. to a particular facet within a classification system.
Any object occurrence can be typed by being assigned to a common object type utilizing this concept. A particular rule, restricting the applicable subtypes of IfcTypeObject that can be assigned, is introduced by overriding this concept at the level of subtypes of IfcObject.
This concept can be applied to the following resources:
An attribute Name and optionally Description can be used for all subypes of IfcObject. For those subtypes, that have an object type definition, such as IfcBeam - IfcBeamType, the common Name and optionally Description is associated with the object type.
Any object occurrence can hold property sets, either directly at the object occurrence as element specific property sets, or at the object type, as type property sets. In this case, the properties that are provided to the object occurrence are the combinations of element specific and type properties. In case that the same property (within the same property set) is defined both in occurrence and type properties, the property value of the occurrence property overrides the property value of the type property.
The body or solid model geometric representation of an IfcProduct is typically defined using a Tessellation or Brep. Subtypes may provide recommendations on other representation types that may be used. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:
The geometric representation of any IfcProduct is provided by the IfcProductDefinitionShape allowing multiple geometric representations. It uses the Product Placement concept utilizing IfcLocalPlacement to establish an object coordinate system, in which all geometric representations are founded.