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_权重

 

 

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;