Roof slab

Definition

The concept of 'Roof slab' defines a slab that is used as a roof, there are separate concepts for ramps and floor slabs. The concept of 'Layered structure (material layers)' is used to define the structure of the roof slab.

Geometry

Geometry type	Extrusion	Profile	Segments	Clipped	Slanted
BoundingBox
Extruded solid	Linear	Rectangular	1	No	No
Extruded solid	Linear	Arbitrary	1	No	No
Extruded solid	Linear	Curved	1	No	No
Extruded solid	Linear	Rectangular	1	No	Yes
Extruded solid	Linear	Arbitrary	1	No	Yes
Extruded solid	Linear	Curved	1	No	Yes
Brep

• Not slanted in the context of roof slabs means, that the extrusion is in the direction of the global Z-axis
• As the basic representation roof slabs should always have a bounding box. The bounding box can be used as a place holder for roof slabs with complex geometry in programs that are not able to support the given geometry. This could be the case e.g. in programs that don't support roof slabs with curved boundaries or Brep representation.
• Some roof slabs can be represented using a single extruded solid that has one segment.
  • Roof slabs that are modeled using a solid may be horizontal, vertical and slanted.
  • Roof slabs may not be clipped. In practice this means that most roof slabs will be represented using Brep geometry. Even if these cases were represented using a clipped solid the design intent behind the clipping would be lost and the slabs would not be more 'intelligent' than when using Brep.
  • Openings into roof slabs are made using the opening element.
  • The roof slab provided by the architect (using architectural CAD) is mostly an approximation and does not contain the full details of the roof composition. This consideration relaxes the requirements that are set for the roof slabs in the current IFC exchange scenarios.
  • When solids are used for the roof slab geometry the exchange files are more compact.
• In all other cases the roof slab representation is made using a Brep
• Clipped roof slabs
• Roof slabs with a profile that can't be expressed by IfcCompositeCurve. The vocabulary of the composite curve contains the following elements: straight segment, circular arc and elliptical arc.
• Curved roof slabs.
• Roof slabs that have a complex geometry.

Used by views

• Arch. design >> Thermal load calculations / HVAC system design
• CAD / visualization

Data structure

IfcSlab
GlobalId
OwnerHistory
Owner history [all]
Label
UserDefinedType
PartOfGroups
Grouping [1,2]
IsContainedBy
Containment [all]
RelatingObject
Building storey [all]
IsDefinedBy
Dynamic property assignment [all]
RelatingPropertyDefinition
PropertySet system [all]
HasProperties
Common slab properties [1,3]
LocalPlacement
Relative placement [all]
PlacementRelTo
Building storey [all]
Representations
Geometric representation [all]
Items
Bounding box geometry [all]
Extruded solid: rectangular [1,3,5]
Extruded solid: arbitrary [all]
Extruded solid: curved [1,2,3,5]
Extruded solid: rectangular, clipped [3,5]
Extruded solid: arbitrary, clipped [3,5]
Extruded solid: curved, clipped [3,5]
Extruded solid: rectangular, slanted [3,5]
Extruded solid: arbitrary, slanted [3,5]
Extruded solid: curved, slanted [3,5]
Extruded solid: rectangular, clipped, slanted [3,5]
Extruded solid: arbitrary, clipped, slanted [3,5]
Extruded solid: curved, clipped, slanted [3,5]
Brep geometry [3,5]
Classification
Classification assignment [none]
Classifications
Classification [none]
HasOpenings
Voids element [1,3,5]
RelatedOpeningElement
Opening element [1,3,5]
PredefinedType
IfcSlabTypeEnum
Roof
LayerInformation
Layered structure (material layers) [1,3,5]
calcSlabArea
calcSlabVolume

Uses concepts

Bounding box geometry [all]
Brep geometry [3,5]
Building storey [all]
Classification [none]
Classification assignment [none]
Common slab properties [1,3]
Containment [all]
Dynamic property assignment [all]
Extruded solid: arbitrary [all]
Extruded solid: arbitrary, clipped [3,5]
Extruded solid: arbitrary, clipped, slanted [3,5]
Extruded solid: arbitrary, slanted [3,5]
Extruded solid: curved [1,2,3,5]
Extruded solid: curved, clipped [3,5]
Extruded solid: curved, clipped, slanted [3,5]
Extruded solid: curved, slanted [3,5]
Extruded solid: rectangular [1,3,5]
Extruded solid: rectangular, clipped [3,5]
Extruded solid: rectangular, clipped, slanted [3,5]
Extruded solid: rectangular, slanted [3,5]
Geometric representation [all]
Grouping [1,2]
Layered structure (material layers) [1,3,5]
Opening element [1,3,5]
Owner history [all]
PropertySet system [all]
Relative placement [all]
Voids element [1,3,5]

Used by concepts

Building storey

Copyright © 2000-2002 BLIS-Project [BLIS, Registered Organization]
Author: Jiri Hietanen (jiri@blis-project.org)
All rights reserved.