Define Generalized Displacements

Form: Generalized Displacements, Generalized Displacements Definition

A generalized displacement is a named displacement measure that is user defined. It is simply a linear combination of displacement degrees of freedom from one or more joints. For example, a defined generalized displacement named "DRIFTX" could be the difference of the UX displacements at two joints on different stories of a building. Another defined generalized displacement named AVGRZ could be the sum of three rotations about the Z axis, each scaled by 1/3.

Generalized displacements are primarily used for output purposes, except that a generalized displacement also can be used to monitor a displacement-controlled nonlinear static analysis.

Use the Advanced > Define > Generalized Displacements command to access the Generalized Displacements form.
Use the buttons on the form to complete the appropriate action:
- Add New Gen Displ button. Click the Add New Gen Displ button to access the Generalized Displacements Definition form.
1. 1. Generalized Displacement Name edit box. Use the default or type in a new name in the edit box.
  2. Type. Choose the type of displacement to be defined:
  - Translational option: The generalized displacement scales (with change of units) as lengths. Coefficients of contributing joint translations are unitless. Coefficients of contributing joint rotations scale as length.
  - Rotational option: The generalized displacement is unitless (radians). Coefficients of joint translations scale as inverse lengths. Coefficients of joint rotations are unitless.
  1. Scale Factors.
    - Add button. Specify the coefficients for any joint translational and/or rotational components that contribute to the definition of the generalized displacement by typing in the appropriate edit boxes. Click the Add button.
    - Modify button. Select the row of data to be modified; type in the necessary changes and click the Modify button.
    - Delete button. Select the row of data to be deleted and click the Delete button.

- Modify/Show Gen Displ button

Select the named generalized displacement to be modified in the Gen Displacements list on the Generalized Displacements form.
Click the Modify/Show Gen Displ button to access the Generalized Displacements Definition form.
Make the necessary changes on the Generalized Displacements Definition form and click the OK button to close the form.

- Delete Gen Displ button
- 1. Select the named generalized displacement to be deleted in the Gen Displacements list on the Generalized Displacements form.
  2. Click the Delete Gen Displ button.

After running an analysis, use the Home > Display > Show Tables command to display the Choose Tables for Display form; click the Joint Output item to display the Displacements item; click the Displacements item to display the Table: Joint Displacement Table item; and then click the OK button to view the generalized displacements assigned to each joint in tabular form.

With a deformed shape displayed, view the displacement components for a single joint by right clicking on a joint. The selected joint is highlighted and values are displayed in a floating Joint Displacements window. Clicking on any other joint updates the display. Clicking anywhere except on a joint closes the Joint Displacements window.