IfcMaterialLayerSetUsage

Definition from IAI: Determines the usage of IfcMaterialLayerSet in terms of its location and orientation relative to the associated element geometry. The location of material layer set shall be compatible with the element geometry (i.e. material layers shall fit inside the element geometry).

EXAMPLE: For a cavity brick wall with extruded geometric representation, the IfcMaterialLayerSet.TotalThickness shall be equal to the wall thickness.

Material layer set is primarily intended to be associated with planar elements with constant thickness. With further agreements on the interpretation of layer set direction, the usage can be extended also to other cases, e.g. to curved elements.

Generally, an element may be layered in any of its primary directions, denoted by its x, y or z axis. However, with geometry use definitions for specific elements, it may become evident which direction is the relevant one for layering.

EXAMPLE: For a standard wall with extruded geometric representation (vertical extrusion), the layer set direction shall be perpendicular to extrusion direction, and coincide with the direction denoting the wall thickness (in positive or negative sense). For a curved wall, "direction denoting the wall thickness" can be derived from the element LCS, but it will remain perpendicular to the wall path.

EXAMPLE: For a slab with vertically extruded geometric representation, the layer set direction shall coincide with the extrusion direction (in positive or negative sense).

Mls usage

Fig 1: shows the use of IfcMaterialLayerSetUsage aligned to the axis of a wall.

EXPRESS specification:

ENTITY IfcMaterialLayerSetUsage;

ForLayerSet

IfcMaterialLayerSet;

LayerSetDirection

IfcLayerSetDirectionEnum;

DirectionSense

IfcDirectionSenseEnum;

OffsetFromReferenceLine

IfcLengthMeasure;

END_ENTITY;

Attribute definitions:

ForLayerSet	:	Layer set to which the usage is applied.
LayerSetDirection	:	Orientation of the layer set relative to element geometry. The meaning of the value of this attribute shall be specified in the geometry use section for each element. For extruded geometric representation, direction can be given along the extrusion path (e.g. for slabs) or perpendicular to it (e.g. for walls).
DirectionSense	:	Denotion whether the layer set is oriented in positive or negative sense along the axis given by LayerSetDirection.
OffsetFromReferenceLine	:	Offset of the material layer set (MlsBase) from reference line. The offset can be positive or negative, unless restricted for a particular building element type in its use definition or by implementer agreement. The reference line for each IfcElement is defined in use definition for the element.

Inheritance graph