Physical Materials
Introduction
Properly capturing the PhysicalMaterial
of a PhysicalElement
is of great importance for Quantity takeoffs and material estimating. Note that in BIS the concept of PhysicalMaterial
is different from RenderMaterial
. The former defines the matter of which physical objects are made while the latter captures the rendering properties of materials for display.
Physical Material class-hierarchy
Physical materials are modeled in BIS using an abstract subclass of DefinitionElement
named PhysicalMaterial
, which is defined in the BisCore schema. More specific subclasses of bis:PhysicalMaterial
are defined in a separate core-layer PhysicalMaterial
schema, covering the main physical materials used in infrastructure. It includes sealed subclasses such as Aggregate
, Aluminum
, Asphalt
and Concrete
. The list of physical materials included in the PhysicalMaterial
schema may grow over time.
In some cases, especially while converting legacy data, the software may not know enough about a physical material to be able to classify it in terms of the classes offered by the PhysicalMaterial
schema. The core-layer Generic
schema includes a generic:PhysicalMaterial
class for those cases.
The following class diagram depicts the PhysicalMaterial
class hierarchy. See Class-diagram Conventions for details about the conventions used.
Physical Materials in Types and Elements
In BIS, the physical material of a physical object is primarily captured by its physical type. The bis:PhysicalType
offers a PhysicalMaterial
navigation property that can be used to refer to the applicable concrete instance of bis:PhysicalMaterial
. That way, any bis:PhysicalElement
referencing a given bis:PhysicalType
shares the same instance of bis:PhysicalMaterial
.
For cases in which a particular instance of bis:PhysicalElement
is made of a different physical material than the one referenced by its bis:PhysicalType
, the bis:PhysicalElement
instance can override it via its own PhysicalMaterial
navigation property.
The following class diagram depicts the relationships between PhysicalElement
, PhysicalType
and PhysicalMaterial
. See Class-diagram Conventions for details about the conventions used.
Modeling perspectives other than Physical may have the need to capture Physical Material information. Each concrete implementation of such modeling perspective may choose to reference PhysicalMaterial
instances in their own way. The following class-diagram shows an example from the StructuralAnalytical
domain (alias sa
). See Class-diagram Conventions for details about the conventions used.
Heterogeneous Assemblies
It is not uncommon to find physical assemblies composed of parts made of different materials. This use-case spans multiple disciplines, from composite walls and structural beams to rigid pavement structures. The approach in BIS explained above associates one and only one PhysicalMaterial
instance for each PhysicalElement
instance. Heterogeneous assemblies are, therefore, accommodated by associating PhysicalMaterial
instances with the parts being assembled rather than the parent assembly.
The following instance-diagram shows an example of a composite beam as an heterogeneous assembly. See Instance-diagram Conventions for details about the conventions used.
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Last Updated: 21 November, 2022