IfcQuantityWeight

IfcQuantityWeight是一个物理元素数量,它定义了一个派生的权重度量来提供元素的物理属性。它通常由测量方法给出的特定测量规则下元素的物理性质导出。

 

示例:建筑构件中使用的钢筋数量可根据其重量进行测量。重量的实际大小取决于所用的测量方法。

IFC2x中增加的新实体。它替换了以前IFC版本中使用的calcXxx属性。

 

Formal Propositions

Rule Description
WR21 If a unit is given, the unit type shall be mass unit. NOTE  There is no distinction between the concept of "Mass" and "Weight" in the current IFC Release.
WR22 A valid weight quantity shall be greater than or equal to zero.
 

 

 

 

IfcQuantityWeight

 

 

Attribute inheritance

# Attribute Type Cardinality Description C
IfcPhysicalQuantity
1 Name IfcLabel [1:1] Name of the element quantity or measure. The name attribute has to be made recognizable by further agreements. X
2 Description IfcText [0:1] Further explanation that might be given to the quantity. X
  HasExternalReferences IfcExternalReferenceRelationship
@RelatedResourceObjects
S[0:?] Reference to an external reference, e.g. library, classification, or document information, that is associated to the quantity. X
  PartOfComplex IfcPhysicalComplexQuantity
@HasQuantities
S[0:1] Reference to a physical complex quantity in which the physical quantity may be contained. X
IfcPhysicalSimpleQuantity
3 Unit IfcNamedUnit [0:1] Optional assignment of a unit. If no unit is given, then the global unit assignment, as established at the IfcProject, applies to the quantity measures. X
IfcQuantityWeight
4 WeightValue IfcMassMeasure [1:1] Mass measure value of this quantity. X
5 Formula IfcLabel [0:1] A formula by which the quantity has been calculated. It can be assigned in addition to the actual value of the quantity. Formulas could be mathematic calculations (like width x height), database links, or a combination. The formula is for informational purposes only. X
 

EXPRESS Specification

ENTITY IfcQuantityWeight
 SUBTYPE OF (IfcPhysicalSimpleQuantity);
  WeightValue : IfcMassMeasure;
  Formula : OPTIONAL IfcLabel;
 WHERE
  WR21 : NOT(EXISTS(SELF\IfcPhysicalSimpleQuantity.Unit)) OR (SELF\IfcPhysicalSimpleQuantity.Unit.UnitType = IfcUnitEnum.MASSUNIT);
  WR22 : WeightValue >= 0.;
END_ENTITY;

 

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