1.1.4 Fabrication

Different structural systems and materials impose their own information requirements and workflows. These have been identified by the Precast Concrete Institute (PCI), American Institute of Steel Construction (AISC), and the American Concrete Institute (ACI).

For fabrication of structural steel and miscellaneous steel (such as for railings), elements contained within a bridge model and their connectivity may be used by a fabricator to elaborate, however typically do not carry sufficient detail to be directly used by CNC machines for automated production. The most common data format in use for this detail is DSTV, commonly having a file extension of "NC1". Information captured for steel fabrication may include:

• Identification of standard shape according to classification scheme.
• Identification of material according to classification scheme.
• Any clippings or copings applied to pieces.
• Any holes to be drilled into pieces.
• Any piece marks applied to pieces, which identify the particular item or type by a coding scheme.
• Any punch marks applied to pieces, which identify points of significance.
• Any contour marks applied to pieces, which may indicate contours.
• Any informational marks applied to pieces, such as weld symbols.
• Nesting of pieces onto feed materials, with location and orientation defined, having a minimum clearance with other shapes, minimizing any waste.
• Grouping of pieces into batches to be delivered together.

NOTE  This exchange currently provides minimal information to be useful for the downstream Design Plans exchange; it is anticipated to be elaborated in a future extension.

Fabrication
Entity/Concept	Attributes	Constraints	I	E
IfcBeam
Structural Curve Assignment	ReferencedBy		R	R
Annotation 2D Geometry	Representation	Identifier Type Items Description     IfcTextLiteralWithExtent Piece marks.     IfcCartesianPoint Pop marks.     IfcIndexedPolyCurve Contour marks.	O	O
Element Positioning	PositionedFrom	Placement Transform Description VERTICAL WARP Bridge girders are positioned and transformed to follow the alignment curve. VERTICAL PLACE Bridge cap beams and diaphragms are positioned without transformation.	O	O
IfcCostItem
Object Nesting	IsNestedBy	Type IfcCostItem	O	O
Control Assignment	Controls	Type Description IfcElement Elements assigned to quantity line item.	R	R
IfcCostSchedule
Object Nesting	IsNestedBy	Type Description IfcCostItem Each quantity line item is nested directly under the cost schedule in order.	R	R
IfcMember
Element Nesting	IsNestedBy	Type PredefinedType IfcMember	O	O
Surface Connectivity	ConnectedFrom	Type IfcPlate	R	R
IfcPlate
Surface Connectivity	ConnectedFrom	Type Description IfcBeam Plates may be attached to beams, functioning as stiffeners or gusset plates.	R	R
Body SweptSolid Extruded Arbitrary Geometry	Representation		O	O
Annotation 2D Geometry	Representation	Identifier Type Items Description     IfcTextLiteralWithExtent Piece marks.     IfcCartesianPoint Pop marks.     IfcIndexedPolyCurve Contour marks.	O	O
Element Nesting	IsNestedBy	Type PredefinedType IfcPlate	R	R
IfcPlateType
Type Body SweptSolid Extruded Arbitrary Geometry	RepresentationMaps		O	O
Type Body SweptSolid Extruded Arbitrary Void Geometry	RepresentationMaps		O	O
IfcProject
Project Declaration	Declares Phase ObjectType LongName	Type Description IfcProjectLibrary Referenced projects incorporated into this project. IfcTypeObject Type definitions defined by this project. IfcActor Actors participating in this project. IfcCostSchedule Quantity takeoff schedules. IfcTask Stages of bridge construction, assigned to corresponding girder framing. IfcStructuralAnalysisModel Structural analysis model with sufficient detail to describe load combinations and results for camber ordinates, but not necessarily full result details. IfcDistributionSystem Distribution systems for drainage or electrical conduit	R	R
Project Units	UnitsInContext Phase ObjectType LongName	DerivedUnitType Description Length unit as meters, millimeters, or inches.	R	R
Project Representation Context	RepresentationContexts Phase ObjectType LongName	ContextIdentifier ContextType Description Model 3D Context for all 3D geometry. Plan 2D Context for all 2D annotations.	R	R
IfcProjectOrder
Aggregation	PredefinedType IsDecomposedBy Decomposes	PredefinedType RelatedObjects Description   IfcCostSchedule A cost schedule may indicate costs and quantities where the cost schedule type may designate whether rates and/or quantities are estimated or final. Such cost schedule may have assigned cost items indicating detail, where each cost item may have assigned products, processes, or resources. WORKORDER IfcWorkSchedule A work schedule may indicate tasks and scheduled times where the work schedule type may designate whether tasks and/or times are planned or actual. Such work schedule may have assigned tasks indicating detail, where tasks may be assigned to products and may have assigned resources.	R	R
IfcRoot
Object Ownership	OwnerHistory		O	O
IfcSlab
Element Positioning	PositionedFrom	Placement Transform Description VERTICAL WARP Bridge decks are positioned and transformed to follow the alignment curve.	O	O
IfcWorkSchedule
Control Assignment	Controls	Type IfcTask	O	O