Steel Linear Elements Properties - EC 3

 

By default, each steel element is calculated using the global steel design assumptions, in conformity with the current standard. The steel assumptions can be defined locally for each element using the options available in the properties window.

 

Accessing the Steel Design Properties of the selected element

To display only the steel design properties of the selected element(s), from the Properties filter drop-down list select Steel Properties.

 

Properties window

 

 

Using the Properties window 

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

 

Key Features and Functions:

1. Clipping of forces

• Clipping: enables the clipping of forces option.

• Extremity: defines the clipping distance for the element extremities. The distance can be automatically calculated by the program or manually defined by the user.

• XY plane: defines if the clipping distance in XY plane is automatically calculated or user defined.

• Value: displays the automatic clipping value for the XY plane. If the user-defined option is enabled, a custom value can be entered.

• XZ plane: defines if the clipping distance in XZ plane is automatically calculated or user defined.

• Value: displays the automatic clipping value for the XZ plane. If the user-defined option is enabled, a custom value can be entered.

 

1. Steelwork Design

• To calculate: when this option is enabled, the element is considered in the steel calculation. When disabled, the concerned element is not calculated.

• Design Results: Displays whether steelwork design results are available for this element.

• Work Ratio: displaying maximum working Ratio value of all design verifications executed inside Advance Design for this element.

• General Design template: you can assign a design template that defines the element design properties. Select one of the available templates from the drop-down list.

• Cross section class: select the cross section class from the drop down list (auto class - the calculation is done automatically, class 1 and 2 - plastic, class 3 and 4 - elastic). To impose the effective characteristics of class 4, click and enter the desired values in the Effective characteristics dialog box.

 

Effective characteristics dialog box

 

 

 

Description of the Effective characteristics dialog box:

• Impose characteristics: When enabled, the user can define the corresponding values.
• Cross section: Defines the value of the effective area. Enter the corresponding value in the Sxeff field.
• Neutral axis offset: Enter values for y and z in the corresponding fields.
• Modules: Enter the effective resistance modules.

Manufacturing quality: select from Class A, Class B or Class C.

 

 

 

1. Advanced stability (2nd order)

• 2nd order with warping and imperfections: Non-linear analysis with 7th degree of freedom (warping) and initial imperfection from scaled dominant eigenvector. Intended when cross-section is not bisymmetrical, but suitable for all cross-section types.

• Number of iterations: select the number of iterations.

• Stability - 2nd order parameters: opens the Advanced stability displacements dialog box.

 

1. Deflections

• Elem. verification: Enable / disable the deflection verification of the element.

  • Define the allowable deflections (1 and 2). Allowable deflection = length of element/n, where "n" is a positive integer.

  • Reference length: Determines the way the reference length for deflection is calculated.

  • L: Reference length for deflection value.

  • Verification location: select from the drop-down list the location on the element for which the deflection are verified (extremity, span, envelope).

• Super Element Verification: Take into account the super element at deflection verification.

  • Define the allowable deflections (1 and 2). Allowable deflection = length of element/n, where "n" is a positive integer.

  • Reference length: Determines the way the reference length for deflection is calculated.

  • L: Reference length for deflection value.

  • Verif. location: select from the drop-down list the location on the element for which the deflection is verified (extremity, span, envelope).

 

1. Buckling

• Elem. verification: Enable / disable the buckling verification of the element. For cable and tie linear elements this verification is disabled.

• Buckling length: allows the definition of buckling lengths for the selected element. In the corresponding cell, click to access the Buckling configuration dialog box.

 

Buckling dialog

 

 

• Shape subject to buckling: specifies if the element is subject to buckling or not. If not, the reduction factors (i.e., min, ky and kz) are not calculated and are considered equal to 1.

• xz plane - large inertia and xy plane - small inertia: define the calculation mode of the buckling lengths for the xy and xz plane of the selected steel element.

  • Cmy,0, Cmz,0: equivalent uniform moment coefficients about local z and y axes.

  • L0: length of the element to the next point of support in the plane buckling.

  • Lfz, Lfy: buckling length about the local y and z axes, associated to the Iz / Iy inertia.

    • Auto calculation: calculates the buckling using the method specified in the Steel design settings dialog box.

    • Imposed value: calculates the buckling lengths by a value entered in the corresponding field.

    • Super-element ratio: calculates the buckling lengths by a specified value multiplied by the super-element length.

    • Element ratio: calculates the buckling lengths by a specified value multiplied by the element length.

    • Mesh size ratio: calculates the buckling lengths by a specified value multiplied by the mesh size.

    • LTB length (upper flange): calculates the buckling length using the value for Upper Flange from the Lateral-torsional buckling settings. This option appears only in weaker axis of the beam.

    • LTB length (lower flange): calculates the buckling length using the value for Lower Flange from the Lateral-torsional buckling settings. This option appears only in weaker axis of the beam.

  • Lfz fire, Lfy fire: define the buckling length for fire verification about z and y local axes.

    • =Lf: the buckling length for fire verification is equal to the buckling length (Lfz or Lfy).

    • Imposed value: calculates the buckling lengths for fire verification by a value entered in the corresponding field.

    • Super-element ratio: calculates the buckling lengths for fire verification by a specified value multiplied by the super-element length.

    • Fixed Lf: calculates the buckling lengths for fire verification by a specified value multiplied by the buckling length (Lfz or Lfy).

    • Mesh size ratio: calculates the buckling lengths for fire verification by a specified value multiplied by the mesh size.

    • Curves: option which allows to choose the imperfection factor (alpha) to be calculated automatically (auto) or be chosen by user according to Table 6.1 in 6.3.1.2 from EN 1993-1-1.

• Nodes (strong axis): specifies if the structure has braced or unbraced nodes, for the xz plane (stronger axis) of the element.

• Nodes (weak axis): specifies if the structure has braced or unbraced nodes, for the xy plane (weak axis) of the element.

The blue highlighted fields display the calculated buckling lengths, Lfz and Lfy, when the steel calculation is completed.

 

 

1. Lateral-torsional buckling

• Elem. verification: Enable / disable the lateral-torsional buckling verification of the element. For cable and tie linear elements this verification is disabled.

• Lateral-torsional buckling length: allows the definition of lateral-torsional buckling lengths for the selected element. Click to access the Lateral-torsional buckling configuration dialog box.

 

 

1. Web buckling

1. Web buckling verification: Enable/disable the web buckling verification of the element.

2. Transverse stiffeners: Define stiffeners perpendicular to the axis of the beam.

• Enable: Enable/disable the transverse stiffeners
• Relative location along element: Displays the relative positions of the transverse stiffeners along the length of the elements with respect to the start point. Click on  to access the Transverse Stiffeners Definition dialog box.

 

Transverse Stiffeners Definition

 

 

• Abscissa: Displays the position of the stiffeners
• Relative: Displays the relative position of the stiffeners
• Add: Add a new transverse stiffener
• Equal Spacings: Distribute the stiffeners evenly along the length of the element
• Remove: Remove the selected stiffener
• Remove all: Remove all stiffeners (except end stiffeners)
• Graphical Definition: The position of the stiffeners can be selected on-screen
• Auto Detect: Auto detection of the stiffeners' positions (intersection with other elements)
• Number: Definition of multiple stiffeners by number (equal spacing)
• Abscissa: Definition of multiple stiffeners by position (distance from the start point of the element)
• Ratio: Definition of multiple stiffeners by relative position (with respect to the start point of the element).

 

3. Longitudinal stiffeners: Define stiffeners along the axis of the element

• Enable: Enable/disable the longitudinal stiffeners
• Number: Number of longitudinal stiffeners along the height of the web (1 or 2)
• Relative position from the bottom of the web: Relative position of longitudinal stiffeners with respect to the height of the beam (starting from the bottom of the web)

• Stiffener 1: Relative position of the longitudinal stiffener 1
• Stiffener 2: Relative position of the longitudinal stiffener 2

• Thickness: Thickness of the longitudinal stiffeners
• Width: Width of the longitudinal stiffeners
• Sides of the web: Location of the longitudinal stiffeners (one side or both sides of the web).

 

 

1. Imperfections EC3

Please note that these properties differ for beams and columns. See below for more details:

1. Columns:

• Global imperfections for y/z local directions: activates the global imperfections on the selected elements

• Φ coefficient for y local direction (small inertia): definition of the global imperfection coefficient (see art. 5.3.2 from EN1993-1-1).

• Φ coefficient for z local direction (large inertia): definition of the global imperfection coefficient (see art. 5.3.2 from EN1993-1-1).

The button displays the Global sway imperfections window:

 

Global sway imperfections

 

 

• Φ0: basic value for global initial sway imperfection; Φ0= 1/200 (see art. 5.3.2 from EN 1993-1-1)

• h: the height of the structure in meters (see art. 5.3.2 from EN 1993-1-1)

• m: is the number of columns in a row including only those columns which carry a vertical load NEd not less than 500/0 of the average value of the column in the vertical plane considered (see art. 5.3.2 from EN1993-1-1)

• αh: the reduction factor for height h applicable to columns (see art. 5.3.2 from EN 1993-1-1)

 

• αm: is the reduction factor for the number of columns in a row:

• Φ: global initial sway imperfections: Φ = Φ0 αh αm     (5.5)

• Local bow imperfections for y/z local directions: activates the local bow imperfections on the selected elements

 

2. Beams:

• Local bow imperfections for weak axis direction: activates the local bow imperfections on the selected elements.

• Weak axis direction:Definition of the weak axis direction (EC3 expression) in a drop-down list:

  • auto = Advance Design detects automatically the smaller inertia direction and generates the equivalent forces on that direction

  • y or z local direction, useful especially in the case of symmetrical cross sections (ex. square sections), when the user applies imperfections on the direction susceptible to strength/stability loss (most unfavorable)

• k (member imperfections): represents the imperfection coefficient for beams.

• k value: set the value for the imperfection coefficient.

 

1. Fire verification - allows to set the fire verification parameters:

• Fire exposure time (min): set the fire exposure period.

• Fire exposure faces: select the number of faces exposed to fire (3 or 4 faces).

 

1. Arcelor castellated beams - allows the definition of castellated beams.

 

1. Angle verification - only for elements with L-type cross section

• Net area: Calculation of the tension resistance based on the net area of the section (with bolts considered in one row), acc. EN 1993-1-8 (§3.10.3).

• Bolt holes on: Angle section leg to put bolt holes on.

• Bolt/Bolt hole: Selection of bolt and hole diameter.

• Bolt nominal diameter: The nominal diameter of bolts. If value is set to Auto, it is selected according the leg length of the angle section.

• d: Bolt diameter value (mm).

• Bolt hole diameter: The diameter of hols for bolts. If value is set to Auto, it is selected according the nominal diameter of a selected bolt.

• d0: Hole diameter value (mm).

• Number of bolts: The number of bolts at one end. Bolts are considered in one row.

• η coefficient: Single angle members with one bolt at each end. Application of a η safety coefficient (η = 0,8) for buckling resistance. Annex G.1(3) from EN1993-3-1.

 

 

Related Topics

• Linear Elements

• Steel Linear Elements