Definitions applying to Bridge View

 Instance diagram

Each pot bearing type is defined using IfcMechanicalFastenerType with PredefinedType set to USERDEFINED and ObjectType set to 'PotBearing'.

Figure 1 — Bridge bearing plans

Figure 1 illustrates an example of pot bearings for supporting girders, where longitudinal-guided bearings are used at abutments, lateral-guided bearings are used at the first pier (supporting circular alignment), and non-guided bearings are used at the second pier (supporting linear alignment).

Figure 2 — Bridge bearing model

As shown in Figure 2, the geometry for the bearings is represented by swept solids for each shape. Masonry plates use IfcExtrudedAreaSolid with a profile cross-section based on IfcArbitraryClosedProfileWithVoids consisting of IfcCircle for each of the anchor bolt holes. Pots use IfcRevolvedAreaSolid with a profile cross-section based on IfcArbitraryClosedProfileDef and IfcIndexedPolyCurve, which is necessary to capture the fillet radius (which would not be possible with IfcExtrudedAreaSolid). Sole plates use IfcExtrudedAreaSolid with a profile-cross-section based on IfcRectangleProfileDef.

Figure 3 — Bridge bearing table

Parameters for bearings could be defined to reflect the dimension tables in the plans as shown in Figure 3 which is a more typical scenario where such dimensions vary. However, this is unnecessary for this particular bridge as all dimensions are the same for each pot bearing type. If parameters were to be defined, IfcRelAssociatesConstraint would link the IfcMechanicalFastenerType to an IfcObjective having ObjectiveQualifier set to PARAMETER. An IfcMetric may have DataValue set to IfcTable, where each IfcTableColumn corresponds to a defined metric. To link dimensions and placements of geometric shapes, IfcMetric is used for each attribute (identified by IfcMetric.ReferencePath) and calculates the value according to IfcMetric.DataValue set to an IfcAppliedValue based on operations of other values (IfcReference) and literals (IfcMeasureWithUnit).

Figure 4 — Bridge bearing placement

Figure 4 illustrates multiple occurrences of bearings which are captured with IfcMechanicalFastener, linked to the IfcMechanicalFastenerType definition using IfcRelDefinesByType. Each bearing occurrence is placed within the bridge structure using IfcRelContainedInSpatialStructure.

Bearing connectivity is captured with IfcRelConnectsWithRealizingElements, where the RelatingElement refers to the bridge pier or abutment (IfcCivilElement), RelatedElement refers to the girder (IfcBeam), and RealizingElements refers to the IfcMechanicalFastener. The ConnectionType attribute may indicate the structural behavior informally.

Each bearing may be linked to a corresponding analytical element in a structural model using IfcRelAssignsToProduct where RelatingProduct refers to the IfcMechanicalFastener and RelatedObjects refers to an IfcStructuralPointConnection. The IfcStructuralPointConnection instance defines fixed or free restraints using IfcBoundaryNodeCondition, and links to analytical representations of supported girders using IfcRelConnectsStructuralMember.

Concept usage

Object Typing

The Object Typing concept applies to this entity as shown in Table 63.

Type IfcMechanicalFastenerType

Table 63 — IfcMechanicalFastener Object Typing

Exchange
Import		O
Export		O

Structural Point Assignment

The Structural Point Assignment concept applies to this entity.

Mechanical behavior of bearings, such as directions of translation and rotation may be described by assigning a structural analysis point connection. Such connection may be part of a full analysis model or may be independent.

Exchange
Import		O
Export		O

Formal representations