IfcStructuralProfileProperties

Definition from IAI: This is a collection of structural properties applicable to all linear structural members having a profile definition. For the structural profile properties a further material dependent specialization is given for taking into account specific profile properties applicable only in the context of a specific building material.

> NOTE: The radii of gyration are not given explicitly but can be derived from moment of inertia and section area. For asymmetric profile the values for alpha and for the moments of inertia of the principle axes can be calculated from MomentOfInertiaY, MomentOfInertiaZ and MomentOfInertiaYZ.

The center of gravity is measured from the origin of the geometric profile definition (see subtypes of IfcProfileDef). The CentreOfGravityInX defines the distance along the geometric x axis of the geometric profile definition, the CentreOfGravityInY defines the distance along the geometric y axis.

- For parameterized profiles: Center of gravity is measured from the center of the profile definition, which is the center of the bounding box of that profile geometry.
- For arbitrary profiles: Center of gravity is measured from the 0.,0. local origin of the underlying 2D coordinate system of the explicit profile definition.

The shear center is measured from the gravity center and is given in the structural coordinates, defined by:

- origin = center of gravity
- y axis = negative x axis of the geometric coordinate system
- z axis = negative y axis of the geometric coordinate system

> HISTORY New entity in Release IFC2x Edition 2.
> IFC2x Edition 3 CHANGE The IfcStructuralProfileProperties has changed by adding the two attributes CentreOfGravityInX and CentreOfGravityInY.

Illustration:

For paramteric profile definitions (here IfcRectangleProfileDef) the center of gravity is relative to the center of the bounding box (geometric center) and in case of profiles symmetrical to both axes it is identical with the center of the bounding box. About the used y- and z-directions: For the profile position a two-dimensional coordinate system is defined (see IfcAxis2Placement2D or black axes in figure). The definition of the profile properties (like MomentOfInertiaY) is given according to the axis convention within structural engineering (red axes in figure). See the figure below. |
Figure 1: Definition of geometric and structural coordinate system | Figure 2: Definition of center of gravity and shear center for arbitrary profile definitions.

EXPRESS specification:

ENTITY IfcStructuralProfileProperties
SUPERTYPE OF | (IfcStructuralSteelProfileProperties)
SUBTYPE OF ( | IfcGeneralProfileProperties);
TorsionalConstantX | : | OPTIONAL IfcMomentOfInertiaMeasure;
MomentOfInertiaYZ | : | OPTIONAL IfcMomentOfInertiaMeasure;
MomentOfInertiaY | : | OPTIONAL IfcMomentOfInertiaMeasure;
MomentOfInertiaZ | : | OPTIONAL IfcMomentOfInertiaMeasure;
WarpingConstant | : | OPTIONAL IfcWarpingConstantMeasure;
ShearCentreZ | : | OPTIONAL IfcLengthMeasure;
ShearCentreY | : | OPTIONAL IfcLengthMeasure;
ShearDeformationAreaZ | : | OPTIONAL IfcAreaMeasure;
ShearDeformationAreaY | : | OPTIONAL IfcAreaMeasure;
MaximumSectionModulusY | : | OPTIONAL IfcSectionModulusMeasure;
MinimumSectionModulusY | : | OPTIONAL IfcSectionModulusMeasure;
MaximumSectionModulusZ | : | OPTIONAL IfcSectionModulusMeasure;
MinimumSectionModulusZ | : | OPTIONAL IfcSectionModulusMeasure;
TorsionalSectionModulus | : | OPTIONAL IfcSectionModulusMeasure;
CentreOfGravityInX | : | OPTIONAL IfcLengthMeasure;
CentreOfGravityInY | : | OPTIONAL IfcLengthMeasure;
WHERE
WR21 | : | NOT(EXISTS(ShearDeformationAreaY)) OR (ShearDeformationAreaY >= 0.);
WR22 | : | NOT(EXISTS(ShearDeformationAreaZ)) OR (ShearDeformationAreaZ >= 0.);
END_ENTITY;

Attribute definitions:

TorsionalConstantX | : | Torsional constant about X-axis of profile coordinate system. Usually measured in [mm4].
MomentOfInertiaYZ | : | Moment of inertia about Y and Z-axes of profile coordinate system. Usually measured in [mm4].
MomentOfInertiaY | : | Moment of inertia about Y-axis of profile coordinate system. Usually measured in [mm4].
MomentOfInertiaZ | : | Moment of inertia about Z-axis of profile coordinate system. Usually measured in [mm4].
WarpingConstant | : | Warping constant of the profile for torsional action. Usually measured in [mm6].
ShearCentreZ | : | Location of the profile's shear centre in the structural Z direction. Mapped on IFC profile coordinate system it is the offset in the direction of the negative Y axis. The offset is relative to the center of gravity. The ShearCentreZ is measured in the global length unit as defined at IfcProject.UnitsInContext.
ShearCentreY | : | Location of the profile's shear centre in the structural Y direction. Mapped on IFC profile coordinate system it is the offset in the direction of the negative X axis. The offset is relative to the center of gravity. The ShearCentreY is measured in the global length unit as defined at IfcProject.UnitsInContext.
ShearDeformationAreaZ | : | Area of the profile for calculating the shear deformation for a shear force parallel to the profile’s Z-axis. Usually measured in [mm2].
ShearDeformationAreaY | : | Area of the profile for calculating the shear deformation for a shear force parallel to the profile’s Y-axis. Usually measured in [mm2].
MaximumSectionModulusY | : | Bending resistance about Y-axis of profile coordinate system at maximum Z-ordinate. Usually measured in [mm3].
MinimumSectionModulusY | : | Bending resistance about Y-axis of profile coordinate system at minimum Z-ordinate. Usually measured in [mm3].
MaximumSectionModulusZ | : | Bending resistance about Z-axis of profile coordinate system at maximum Y-ordinate. Usually measured in [mm3].
MinimumSectionModulusZ | : | Bending resistance about Z-axis of profile coordinate system at minimum Y-ordinate. Usually measured in [mm3].
TorsionalSectionModulus | : | Torsional resistance (about the profiles X-axis). Usually measured in [mm3].
CentreOfGravityInX | : | Location of the profile's centre of gravity in the geometric X direction. The CentreOfGravityInX is measured in the global length unit as defined at IfcProject.UnitsInContext. IFC2x Edition 3 CHANGE The attribute CentreOfGravityInX is a new attribute.
CentreOfGravityInY | : | Location of the profile's centre of gravity in the geometric Y direction. The CentreOfGravityInY is measured in the global length unit as defined at IfcProject.UnitsInContext. IFC2x Edition 3 CHANGE The attribute CentreOfGravityInY is a new attribute.

Formal Propositions:

WR21 | : | The shear deformation area y shall have a value, if given, being greater than zero.
WR22 | : | The shear deformation area z shall have a value, if given, being greater than zero.

Inheritance graph

ENTITY IfcStructuralProfileProperties;
ENTITY IfcProfileProperties;
ProfileName | : | OPTIONAL IfcLabel;
ProfileDefinition | : | OPTIONAL IfcProfileDef;
ENTITY IfcGeneralProfileProperties;
PhysicalWeight | : | OPTIONAL IfcMassPerLengthMeasure;
Perimeter | : | OPTIONAL IfcPositiveLengthMeasure;
MinimumPlateThickness | : | OPTIONAL IfcPositiveLengthMeasure;
MaximumPlateThickness | : | OPTIONAL IfcPositiveLengthMeasure;
CrossSectionArea | : | OPTIONAL IfcAreaMeasure;
ENTITY IfcStructuralProfileProperties;
TorsionalConstantX | : | OPTIONAL IfcMomentOfInertiaMeasure;
MomentOfInertiaYZ | : | OPTIONAL IfcMomentOfInertiaMeasure;
MomentOfInertiaY | : | OPTIONAL IfcMomentOfInertiaMeasure;
MomentOfInertiaZ | : | OPTIONAL IfcMomentOfInertiaMeasure;
WarpingConstant | : | OPTIONAL IfcWarpingConstantMeasure;
ShearCentreZ | : | OPTIONAL IfcLengthMeasure;
ShearCentreY | : | OPTIONAL IfcLengthMeasure;
ShearDeformationAreaZ | : | OPTIONAL IfcAreaMeasure;
ShearDeformationAreaY | : | OPTIONAL IfcAreaMeasure;
MaximumSectionModulusY | : | OPTIONAL IfcSectionModulusMeasure;
MinimumSectionModulusY | : | OPTIONAL IfcSectionModulusMeasure;
MaximumSectionModulusZ | : | OPTIONAL IfcSectionModulusMeasure;
MinimumSectionModulusZ | : | OPTIONAL IfcSectionModulusMeasure;
TorsionalSectionModulus | : | OPTIONAL IfcSectionModulusMeasure;
CentreOfGravityInX | : | OPTIONAL IfcLengthMeasure;
CentreOfGravityInY | : | OPTIONAL IfcLengthMeasure;
END_ENTITY;