Plastic Hinge Definition

Introduction

The Plastic hinge definition dialog box allows you to define the properties of the plastic hinge.

 

How to access the command

 

Plastic hinge definition dialog box – Auto defined

By default, when enabling a plastic hinge, the Definition is set to “Auto defined”, the Code is set with respect to the norms used for the model and the Type is set according to the type of the element. See figure below for more details.

Plastic hinge definition dialog box – Auto defined

Overview
  1. Direction: it can be enabled/disabled each DOF on which the plastic hinge is defined. The plastic hinge properties can be defined independently on each DOF.

  2. Definition: when set to “Auto defined” – the hinge properties are computed automatically; when set to “User defined” - the hinge properties can be customized.

  3. Code: hinge properties can be defined either with respect to “FEMA 356:2000” or “EC 8-3:2005”.

  4. Type: A different list of plastic definitions is available for each combination of Code (FEMA 356 or EC8-3), material (steel or concrete) and DOF (Tx, Ry. Rz).

  5. Template: a predefined plastic hinge can be loaded.

  6. Yield Bending Moment - the value of the bending moment at which the plastic hinge will develop. This value is computed during the analysis.

  7. Yield Rotation – the rotation at yielding of the cross-section at the location of the hinge. This value is computed during the analysis. Used for the computation of the limit states – in the codes, the limit states are defined as a ratio of the yield rotation.

  8. Acceptance criteria/limit states - The limit states are calculated with respect to the selected Type, in accordance with the code (both in FEMA and EC 8-3 limit states are tabulated).

  9. Normalized – When enabled, the plastic hinge diagram and the limit states are displayed as a ratio of the Yield Rotation/Yield Bending Moment. After the analysis, when the plastic hinge results are available, Normalized can be disabled and the effective values are displayed.

  10. Symmetric – a hinge is symmetric +/-. Used for the definition of the hinge Parameters.

  11. Display acceptance criteria/limit states on graph – Toggles on/off the display of the limit states on the graph.

  12. Displays the sign convention of the degrees of freedom – arrow indicates positive sign for Tx, My and Mz.

  13. Preview – displays the plastic hinge moment-rotation law.

  14. Customize hinge – when enabled, the plastic hinge Parameters can be modified.

  15. Parameters – define the plastic hinge moment-rotation law.

 

Plastic hinge definition dialog box – User defined

When the plastic hinge Definition is set to User defined (1.) the Yield Bending Moment, Yield Rotation and the Acceptance Criteria/Limit States can be imposed. This can be performed by checking the Custom checkbox (2.). Several or all parameters can be customized. The parameters for which the Custom checkbox is unchecked are computed by the software.

Moreover, when the plastic hinge Definition is set to User defined (1.), the Customize hinge checkbox (3.) can be enabled. When enabled, the Parameters defining the plastic hinge moment-rotation law can be modified.

Plastic hinge definition dialog box  – User defined

Ratios for Acceptance criteria

In the Plastic Hinges parameter definition window, you can also enter parameters (ratios) used for determining Acceptance Criteria. The Properties button opens an additional dialog box. The dialog is linked to the DOF of the plastic hinge and can be opened independently for each direction.

Additional ratio properties of plastic hinges

Additional ratio properties of plastic hinges

 

The availability of the button as well as the number and type of parameters depends on the type of hinge - for this purpose, there are 4 different types of dialog boxes, which are automatically selected according to the type of hinge.

Parameters are determined for the following hinge types:

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