7.3.3.7 IfcConstructionResource

Ressource de construction
Konstruktion - Ressource

IfcConstructionResource is an abstract generalization of the different resources used in construction projects, mainly labour, material, equipment and product resources, plus subcontracted resources and aggregations such as a crew resource.

A resource represents "use of something" and does not necessarily correspond to a single item such as a person or vehicle, but represents a pool of items having limited availability such as general labor or an equipment fleet. A resource can represent either a generic resource pool (not having any task assignment) or a task-specific resource allocation (having an IfcTask assignment).

HISTORY  New entity in IFC2x2.
IFC4 CHANGE  Modified in to promote ResourceIdentifer and ResourceGroup (renamed to LongDescription) to supertype IfcResource and add attributes as described.

Declaration use definition

A root-level resource (specifically IfcCrewResource or IfcSubContractResource) is declared within the project by IfcRelDeclares where RelatingContext refers to the single IfcProject and RelatedObjects refers to one or more IfcConstructionResource, and other root-level objects within the project.

Assignment use definition

A resource may be assigned to an actor by IfcRelAssignsToActor where RelatingActor refers to an IfcActor and RelatedObjects refers to one or more IfcConstructionResource or other objects. Such relationship indicates the actor responsible for allocating the resource such as partitioning into task-specific allocations, delegating to other actors, and/or scheduling over time. Note that this assignment does not indicate the person or organization performing the work; that is indicated by IfcRelAssignsToResource. The actor responsible for the resource may or may not be the same as any actor(s) performing work.

A resource may be assigned to a control by IfcRelAssignsToControl where RelatingProduct refers to an IfcControl and RelatedObjects refers to one or more IfcConstructionResource or other objects. Most commonly an IfcWorkCalendar is assigned indicating availability of the resource, where such calendar is nested within a base calendar or an IfcWorkPlan which in turn is assigned to the IfcProject.

A resource may be assigned to a group by IfcRelAssignsToGroup where RelatingGroup refers to an IfcGroup and RelatedObjects refers to one or more IfcConstructionResource or other objects. Most commonly an IfcAsset is assigned indicating the asset to be tracked, where such asset is nested within an IfcInventory which in turn is assigned to the IfcProject.

A resource may be assigned to a product by IfcRelAssignsToProduct where RelatingProduct refers to an IfcProduct and RelatedObjects refers to one or more IfcConstructionResource or other objects. Most commonly an IfcElement subtype is assigned indicating the product to be constructed, where such product is connected to a spatial structure which in turn is aggregated within the IfcProject.

A resource may be assigned to a process by IfcRelAssignsToProcess where RelatingProcess refers to an IfcProcess and RelatedObjects refers to one or more IfcConstructionResource or other objects. Most commonly an IfcTask is assigned indicating the task to be performed by the resource, where such task is nested within a summary task which in turn is assigned to the IfcProject.

A resource may have assignments of other objects using IfcRelAssignsToResource where RelatingResource refers to the IfcConstructionResource and RelatedObjects refers to one or more objects such as IfcActor or IfcProduct subtypes. This relationship indicates specific objects assigned to fulfill resource usage.

Figure 263 illustrates resource assignment.

Assignment Use Definition

Figure 263 — Construction resource assignment use

Baseline use definition

A resource may have any number of baselines defined using the relationship IfcRelDefinesByObject where RelatingObject is the "current" resource and RelatedObjects consists of multiple "baseline" resources, each representing a copy of the resource as it existed at an earlier point in time as shown in Figure 185. Each baseline IfcConstructionResource is identified by its nested IfcRelAssignsToControl relationship to an IfcWorkSchedule having PredefinedType=BASELINE, IfcWorkSchedule.CreationDate indicating the date of the baseline, and IfcWorkSchedule.Name indicating the name of the baseline.

Baseline Use Definition

Figure 264 — Construction resource baseline use


Common Use Definitions

The following concepts are inherited at supertypes:

 Instance diagram

Object Documentation

The Object Documentation concept applies to this entity.

Documents may be published for work plans consisting of schedules, calendars, tasks, and resources. The relationship IfcRelAssociatesDocument may be used to preserve mappings to such document where RelatingDocument points to an IfcDocumentReference and RelatedObjects includes the IfcConstructionResource as shown in Figure 184. IfcDocumentReference.ItemReference identifies the resource within the scope of the document, such as an integer or guid. The IfcDocumentReference.ReferencedDocument corresponds to the document which is uniquely identified by IfcDocumentInformation.DocumentId and/or IfcDocumentInformation.PublicationLocation. Such document mapping allows items in the document to be updated from the building information model and vice-versa.

Document Use Definition

Figure 265 — Construction resource document use



Object Constraint

The Object Constraint concept applies to this entity as shown in Table 302.
DataValueAttribute1Attribute2Description
IfcPositiveRatioMeasureUsageScheduleUsageIndicate fixed usage (such as simultaneous workers) such that changes to ScheduleWork should impact the assigned IfcTask.TaskTime.ScheduleDuration and vice-versa.
IfcDurationUsageScheduleWorkIndicate fixed work (such as total person-hours) such that changes to ScheduleUsage should impact the assigned IfcTask.TaskTime.ScheduleDuration and vice-versa.

Table 302 — IfcConstructionResource Object Constraint

Constraints may be applied to a resource to indicate fixed work (such as total person-hours) or fixed usage (such as simultaneous workers).



Object Typing

The Object Typing concept applies to this entity as shown in Table 303.
Type
IfcConstructionResourceType

Table 303 — IfcConstructionResource Object Typing

The resource type may provide shared productivity and cost information, allowing tasks and resources to be selected according to lowest cost and/or shortest duration. Given an IfcProduct of a particular IfcTypeProduct type, an IfcTypeProcess may be selected from those assigned to the product type using IfcRelAssignsToProduct, and an IfcTypeResource may be selected from those assigned to the process type using IfcRelAssignsToProcess. Then IfcTask and IfcConstructionResource occurrences may be instantiated from the type definitions, applying productivitity and rate information to assigned quantities to calculate ResourceTime.ScheduleWork. Task durations can then be calculated by dividing ResourceTime.ScheduleWork by ResourceTime.ScheduleUsage.

Type Use Definition

Figure 266 — Construction resource type use



Property Sets for Objects

The Property Sets for Objects concept applies to this entity as shown in Table 304.
PredefinedTypeName
 Pset_ConstructionResource

Table 304 — IfcConstructionResource Property Sets for Objects

For time series properties as shown in Figure 180, each IfcTimeSeriesValue indicates a LIST of values, where the sequence of the value corresponds to the IfcCostValue at IfcConstructionResource.CostRatesConsumed. For example, if CostRatesConsumed has two IfcCostValue items in the LIST, "Standard" and "Overtime", then IfcTimeSeriesValue(IfcDuration('T8H0M0S'),IfcDuration('T2H0M0S')) would indicate 8 hours at Standard rate and 2 hours at Overtime rate. If the list of values at IfcTimeSeriesValue.ListValues is less than the size of CostRatesConsumed, then subsequent values are considered to be zero.

Time Series Use Definition

Figure 267 — Construction resource time series use



Object Nesting

The Object Nesting concept applies to this entity as shown in Table 305.
Type
IfcConstructionResource

Table 305 — IfcConstructionResource Object Nesting

Resources may be decomposed into allocation pools using the IfcRelNests relationship as shown in Figure 181. For example, an IfcLaborResource for "Electrician" may be decomposed into three task-specific IfcLaborResource objects: "Electrical Rough-in", "First Floor Circuits", and "Second Floor Circuits". Both relating and related sides may represent the same ResourceTime.ScheduleUsage quantity (for example, 6 workers time-shared), or the related side may break out ResourceTime.ScheduleUsage quantities for reserved use (for example, 4 workers and 2 workers).

A common scenario is two nesting levels where the first-level resources have no task assignments; while second-level resources have specific task assignments indicating that the resource is subdivided into allocations for specific tasks. While the model allows unlimited nesting of resources, implementer agreements may restrict to two nesting levels with task assignments specifically at the second level.

Composition Use Definition

Figure 268 — Construction resource composition use




XSD Specification:

 <xs:element name="IfcConstructionResource" type="ifc:IfcConstructionResource" abstract="true" substitutionGroup="ifc:IfcResource" nillable="true"/>
 <xs:complexType name="IfcConstructionResource" abstract="true">
  <xs:complexContent>
   <xs:extension base="ifc:IfcResource">
    <xs:sequence>
     <xs:element name="Usage" type="ifc:IfcResourceTime" nillable="true" minOccurs="0"/>
     <xs:element name="BaseCosts" nillable="true" minOccurs="0">
      <xs:complexType>
       <xs:sequence>
        <xs:element ref="ifc:IfcAppliedValue" maxOccurs="unbounded"/>
       </xs:sequence>
       <xs:attribute ref="ifc:itemType" fixed="ifc:IfcAppliedValue"/>
       <xs:attribute ref="ifc:cType" fixed="list"/>
       <xs:attribute ref="ifc:arraySize" use="optional"/>
      </xs:complexType>
     </xs:element>
     <xs:element name="BaseQuantity" type="ifc:IfcPhysicalQuantity" nillable="true" minOccurs="0"/>
    </xs:sequence>
   </xs:extension>
  </xs:complexContent>
 </xs:complexType>

EXPRESS Specification:

ENTITY IfcConstructionResource
ABSTRACT SUPERTYPE OF(ONEOF(IfcConstructionEquipmentResource, IfcConstructionMaterialResource, IfcConstructionProductResource, IfcCrewResource, IfcLaborResource, IfcSubContractResource))
SUBTYPE OF IfcResource;
Usage : OPTIONAL IfcResourceTime;
BaseCosts : OPTIONAL LIST [1:?] OF IfcAppliedValue;
BaseQuantity : OPTIONAL IfcPhysicalQuantity;
END_ENTITY;

Link to EXPRESS-G diagram EXPRESS-G diagram

Attribute Definitions:

Usage : Indicates the work, usage, and times scheduled and completed. Some attributes on this object may have associated constraints or time series; see documentation of IfcResourceTime for specific usage. If the resource is nested, then certain values may be calculated based on the component resources as indicated at IfcResourceTime.
IFC4 CHANGE  New attribute.
BaseCosts : Indicates the unit costs and environmental impacts for which accrued amounts should be calculated. Such unit costs may be split into Name designations (for example, 'Standard', 'Overtime'), and may contain a hierarchy of cost values that apply at different dates (using IfcCostValue.ApplicableDate and IfcCostValue.FixedUntilDate).
IFC4 CHANGE  New attribute.
BaseQuantity : Identifies the base quantity consumed of the resource relative to assignments. For crew, labour, subcontract, and equipment resources, this refers to IfcQuantityTime. For material resources, this refers to IfcQuantityVolume. For product resources, this refers to IfcQuantityCount.
IFC4 CHANGE  New attribute.

Inheritance Graph:

ENTITY IfcConstructionResource
ENTITY IfcRoot
GlobalId : IfcGloballyUniqueId;
OwnerHistory : OPTIONAL IfcOwnerHistory;
Name : OPTIONAL IfcLabel;
Description : OPTIONAL IfcText;
ENTITY IfcObjectDefinition
INVERSE
HasAssignments : SET OF IfcRelAssigns FOR RelatedObjects;
Nests : SET [0:1] OF IfcRelNests FOR RelatedObjects;
IsNestedBy : SET OF IfcRelNests FOR RelatingObject;
HasContext : SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions;
IsDecomposedBy : SET OF IfcRelAggregates FOR RelatingObject;
Decomposes : SET [0:1] OF IfcRelAggregates FOR RelatedObjects;
HasAssociations : SET OF IfcRelAssociates FOR RelatedObjects;
ENTITY IfcObject
ObjectType : OPTIONAL IfcLabel;
INVERSE
IsDeclaredBy : SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects;
Declares : SET OF IfcRelDefinesByObject FOR RelatingObject;
IsTypedBy : SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects;
IsDefinedBy : SET OF IfcRelDefinesByProperties FOR RelatedObjects;
ENTITY IfcResource
Identification : OPTIONAL IfcIdentifier;
LongDescription : OPTIONAL IfcText;
INVERSE
ResourceOf : SET OF IfcRelAssignsToResource FOR RelatingResource;
ENTITY IfcConstructionResource
Usage : OPTIONAL IfcResourceTime;
BaseCosts : OPTIONAL LIST [1:?] OF IfcAppliedValue;
BaseQuantity : OPTIONAL IfcPhysicalQuantity;
END_ENTITY;

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