Finite Linear Elements Properties

 

The properties window is an essential tool for viewing and modifying the properties of finite linear elements. This functionality is crucial for the precise configuration and optimization of element behaviors in your models.

 

 

Accessing the Finite Element Properties

To focus only on finite element properties, select FE Properties from the Properties filter drop-down list. This action filters the display to show only the attributes relevant to finite element analysis, providing a clearer and more simple interface.

 

Properties window

 

Using the Properties window for Finite Linear Elements

In the properties window, you can view and modify the properties of finite linear elements, allowing for detailed customization and management.

 

Key Features and Functions:

 

1. General

 

• Identifier: View / modify the ID number of the element.

• Name: View / modify the default name of the element.

 

Tip: Elements with different properties (material, cross section, etc.) can share the same name that can be used as a selection criteria.

 

• Type: Select a linear element type from the drop-down list (i.e., bar, short beam, variable beam, tie, gap, cable, beam).

• Active state: The state of the element. When the disabled, the element becomes inactive and its properties can no longer be modified.

• Systems: View the ID of the system in which the element is located.

• Comment: Insert observations regarding the element.

• GTC Identifier: The identifier automatically assigned to the element after the GTC export / import.

 

 

1. Super element (grouping and processing a set of finite elements)

 

• Identifier: View the ID number of the super element.

• List: View the ID number of the elements comprised in the super element.

• Color: View / modify the color of the super element.

 

 

1. Material

 

Select a material type for the linear element. Place the cursor in the Code cell and click to display the Materials dialog box. The material types used in Advance Design are steel, concrete and timber.

 

 

1. Cross section

 

• Extremity: define the cross section parameters for each extremity of the linear element.

• Click to open the Cross section libraries dialog box and select a cross section type from a library.
• Click to open the Compound cross sections dialog box and define a compound cross section.
• Click  to open the Defined dialog box and configure the cross section parameters (i.e., material, shape, sizes).
• Enter the cross section code or from the drop-down list select an existing one.

 

• Eccentricity: refers to the position of a cross section relative to its axis. You can select a defined type from the Option drop-down list:

  • (y+, z+) – moves element so it is completely in the positive part of y and z axis of the local system and its two walls coincide with the xy and xz planes of the local system.

 

 

• (Y+, 0) - moves element so it is completely in the positive part of y axis of the local system and one of its wall coincides with the xz plane of the local system.

 

• (Y+, z-) - moves element so it is completely in the positive part of y and negative of z axis of the local system and its two walls coincide with the xy and xz planes of the local system.

 

• (0, z+) - moves element so it is completely in the positive part of z axis of the local system and one of its wall coincides with the xy plane of the local system.

 

• (0, 0) – element offset is to equal 0 in both y and z axis, so x axis is running throw center of mass of the element.

 

• (0, z-) - moves element so it is completely in the negative part of z axis of the local system and one of its wall coincides with the xy plane of the local system.

 

• (Y-, z+) - moves element so it is completely in the negative part of y axis and positive of z axis of the local system and its two walls coincide with the xy and xz planes of the local system.

 

• (Y-, 0) - moves element so it is completely in the negative part of y axis of the local system and one of its wall coincides with the xz plane of the local system.

 

• (Y-, z-) - moves element so it is completely in the negative part of y and negative of z axis of the local system and its two walls coincide with the xy and xz planes of the local system.

 

• select Other and enter the eccentricity values in the cells. The linear element offset is defined around its weight center by the three local axes. User can easily implement their offset of the two points each placed on the end of the linear element.

  • Y1 - Transversal eccentricity of section along the local y axis at end of the linear element

  • Y2 - Transversal eccentricity of section along the local y axis at the 2nd end of linear element

  • Z1 - Transversal eccentricity of section along the local z axis at 1st end of the linear element

  • Z2 - Transversal eccentricity of section along the local z axis at the 2nd end of linear element

  • Considered FEM - Decide whether or not the offset is taken into account in the FEM calculation, by enabling or disabling offset in FEM calculation

 

• Concrete inertia type - dropdown list - available only for concrete element when automatic factor modifications corresponding to standards of some codes (i.e. EC8, P100) automatically defines these coefficients for different elements (beams, columns, etc.). Selection of the method of considering the stiffness of a concrete element for FEM calculations: With using modified cracked inertia for bending, calculated during RC cracking verification OR With using imposed values of inertia coefficients.

• Auto - Uses modified cracked inertia for bending, calculated during RC cracking verification. If no cracking occurs no calculation in RC sequence , the modifiers remains with their imposed values.
• Imposed value - Use imposed values of geometric modifiers defined in FEM calculations.

 

• Cracked section inertia coefficients – considering the element stiffness in the stiffness matrix, those factors are multiplying the E or G value for the corresponding element.

Effective stiffness

 

 

• Bending stiffness (strong axis) – defines bending stiffness along the stronger axis of the element.
• Bending stiffness (weak axis) – defines bending stiffness along the weaker axis of the element.
• Torsional stiffness - defines torsional stiffness of the element.
• Axial stiffness – defines axial stiffness of the element.

 

• Product of inertia Iyz = 0 - Enabling this option causes the moment of inertia Iyz to be disregarded (zeroed out) for the profile during FEM calculations. This option can be useful when analyzing non-symmetric profiles (including cold forms such as Z) where, although the element is analyzed according to u-v (principal axis) stresses, deflections are calculated in the x-y axis system.

 

This option is a way to model the behavior of asymmetrical profiles attached by a flange to a cover sheet (roof sheet, which is not modeled). Such a sheet is blocked by default from moving sideways (in the y direction of the local layout of the element). Normally for asymmetrical profiles due to load perpendicular to the upper flange after FEM calculations we obtain deflection which has components downwards and sideways (local z and y directions).  If the moment of inertia Iyz (which for unsymmetrical profiles is different from zero) is zeroed, then after the FEM calculation we do not obtain a deflection component in the horizontal direction (local y).

 

 

1. Haunches - Create haunches and define their properties

Haunches can be placed at the start and/or at the end of a steel linear element, above, below or on both sides of the end. The linear element must have an I or H cross section.

 

Haunches properties are defined in the linear element properties window, Haunches category.

 

 

• Position: defines the position of the haunch (above, below or on the both sides of the element).

• Length: allows the selection of the length definition type: Ratio, Value (local axis) or Projected value.

• Ratio: allows the definition of the length of the haunch considering the length of the element on which the haunch is applied. The haunch length is a percent of the element length.

• Value: the length of the haunch. It can be manually imposed.

• Cross section type: allows the definition of the haunch cross section. The available options are: Identical - the haunch cross section is the same as the element on which is applied, Next shape - the next cross section from the library is selected, Previous shape - the previous cross section from the library is selected.

• Cross section: allows the selection of the haunch cross section from the libraries / definition the properties of a symmetric I shaped cross section.

• Height: allows the definition of the height definition type: Ratio or Value.

• Ratio: allows the definition of the height of the haunch considering the height of the element on which the haunch is applied. The haunch height is a percent of the element height.

• Value: the height of the haunch. It can be manually imposed.

 

 

1. Orientation

 

• Angle: Input a value in degrees for the linear element's orientation angle.
• Point: Input the ID of an existing point to which the linear element orientation should refer. For more details refer to these pages: Points properties and Linear Elements. 

 

 

1. Releases

 

• Total releases: Lock / unlock the translations and rotations for object extremities on the X, Y and Z axes. These settings are important for the calculation step.
• Elastic releases: Define the spring translations and rotations for object extremities on the X, Y and Z axes. Click to open the Elastic Releases dialog box and specify the abscissa and ordinate coordinates for the linear element elastic releases. For object extremities, it is possible to define the spring degrees of freedom in translation and rotation on the x, y and z local axes by specifying the translational stiffness - displacement (or rotational stiffness – rotation) relation.

• Abscissas (m or °): Defines the displacement (or rotation) value.
• Ordinates (kN/m or kN/°): Defines the rigidity value.
• Insert: Adds a new line in the table, in order to define the points of the translational stiffness - displacement (or rotational stiffness – rotation) curve.
• Delete: Deletes the selected row from the table.

• Plastic hinges:

 

1. Eccentricity – represents the position of the plastic hinge along the local X axis of the element with respect to the corresponding extremity. The value of Clipping of forces is defined according to the Eccentricity. It is set on the corresponding planes with respect to the directions on which the plastic hinges are enabled. This is performed to consider the internal forces diagrams up to the location of the plastic hinges.

2. ID of the plastic hinge.

3. Definition - each plastic hinge has its unique ID that contains some information regarding the hinge position and its type.

 

• For example, the meaning of the “PLH-L112-1 C” ID is:
• “PLH” – plastic hinge;
• “L112” – the plastic hinge is positioned on linear element 112;
• “1” – the plastic hinge is positioned at extremity 1;
• “C” – the element is a column.

The software will detect whether the element is a column (vertical element), or if it is a beam (horizontal or inclined element) and will assign by default the appropriate hinge type.

 

4. Enable/Disable the plastic hinge on the corresponding degree of freedom (DOF). There are three degrees of freedom (DOF) on which the hinges can be applied::

• Tx – axial plastic hinge, along the local X axis;
• Ry – flexural plastic hinge, around the local Y axis;
• Rz – flexural plastic hinge, around the local Z axis.

The plastic hinges can be enabled at both ends of the element: Extremity 1 – start of the element and Extremity 2 – end of the element. Hence, each element can have two plastic hinges.

The properties of the plastic hinge can be defined by opening the “Plastic hinge definition” dialog box from the icon.

 

 

1. Cost and CO2 calculations

Cost estimations

• Settings by material: When enabled (default) the unit cost is considered as defined on Material.
• Unit costs: Field becomes enabled when "Settings by material" is disabled. Unit cost can be set to None, if is desired not to be accounted in overall cost estimation. If Unit prices Sets were previously defined, one of them can be chosen from the drop–down list. By clicking , the Unit Prices Manager dialog box will open, and Unit prices can be defined.

 

CO2 emission 

• Settings by material: When enabled (default) the Carbon factors are considered as defined on Material.
• Carbon Factors: Field becomes enabled when "Settings by material" is disabled.  Carbon factors can be set to None, if is desired not to be accounted in overall carbon emission estimation.  If Carbon Factors Sets were previously defined, one of them can be chosen from the drop –down list. By clicking  , the Carbon Factors Manager dialog box will open, and Carbon Factors can be defined.

 

 

1. Initial constraint

 

Linear elements are subjected to axial constraints. Therefore, the desired values for the initial axial stresses can be entered for a specific load case:

• Load Case: Initial axial stress applied for the specific load case.
• Uniform axial stress Sxx: Initial Axial stress distributed uniformly all over the section.
• y gradient of axial stress Sxx: Initial axial stress variation per unit length of the section in the local y direction.
• z gradient of axial stress Sxx: Initial axial stress variation per unit length of the section in the local z direction.

 

 

1. Mesh

 

The meshing of all linear elements is defined according to the global mesh settings. The meshing parameters for each linear element can be defined locally using the properties window:

• Automatic: when enabled, nodes are created at each intersection with the neighbored elements. When disabled, element meshing is solved internally without creating nodes with the intersecting elements.

The linear element meshing is defined using the Parameters fields:

 

• Number: The number of meshes along the linear element.
• Size: The size of a mesh element.
• Spacing: The spacing between mesh nodes along the linear element.
• Secondary size: Define the size of meshes along an element using the first defined size. The size of meshes will vary between the first and the second size values.

• Extend into the wall: when enabled, if the linear element is connected to a planar element, the linear element is automatically extended over one mesh of the planar element.

 

1. Behavior coefficient

 

• System: Input the ID of system from which the linear element inherits the behavior characteristics.

 

 

1. Load Area Transfer

 

• Supporting element: When enabled, the linear element is a supporting element for snow and wind loads.

• Lattice structure or scaffolding: When enabled, the software applies the wind loads directly on the truss elements and not on the load areas. The force coefficient cf,0 is defined automatically according to Tables 7.33, 7.34 and 7.35 of EN 1991-1-4.

• Parapet max snow load shape coeff (μ): This parameter is editable only for parapet walls (when Type parameter in the Climatic Behavior group is set as the Parapet Wall). It allows you to decide the maximum value of the snow load shape coefficient μ2. This coefficient is used during calculation of drifting snow on roofs having parapet walls, according to point 6.2 of EN 1991-1-3. There are three options available:

• Auto – the limit for the μ2 coefficient is set automatically (for flat roofs and mono-pitched roofs having a slope smaller than 5 degrees).
• 1.6 – the μ2 coefficient is limited to 1.6
• 2.0 – the μ2 coefficient is limited to 2.0

 

Tip: Click a section of the properties window. Notice the bottom area of the window; it displays a short description of the cell's current content.

 

 

1. Clipping

 

 

1. Enable/Disable the offset, from the extremity of the element, of the diagrams of internal forces.

2. Automatic – clipping of forces at the face of the connected/intersected element  - Imposed – user-defined value

 

Accessing the properties

• In the Project Browser, expand the model Structure and select a linear element.

• In the graphic area, select a linear element.

 

When there are more linear elements selected, the properties window displays their common properties.

 

 

Related topics

• How to create haunches for steel beams

• How to design a beam to wall connection

• How to modify the mesh on linear elements