Load Case Data - Buckling Form

When the Load Case Type is Buckling , use the form to view and change the definition of a buckling load case. A buckling analysis is always linear.

Note: Please refer to the Load Case Data Form topic for information related to the Load Case Name edit box, the Load Case Type and Load Case Subtype drop-down lists, and the Notes Modify/Show and Design buttons.

P-Delta/Nonlinear Stiffness options.
- Use Preset P-Delta Settings option. Click the Modify/Show button to access the Preset P-Delta Options form. Use that form to set the P-Delta analysis parameters.
- Use Nonlinear Case (Loads at End of Case NOT Included) option. Choose to solve the buckling nodes starting at the end of a nonlinear load case. Use the drop-down list to select the load case.
Loads Applied. Buckling modes are always calculated with respect to a set of applied loads. Different buckling modes will result from different sets of loads. The loads from one or more load patterns or built-in acceleration loads may be applied.

Important: All loads specified will be added and applied in combination. Only a single response will be calculated. Create different load cases to obtain separate responses to separate loads.

- Load Type. Choose to apply a load pattern or a built-in acceleration load.
- Load Name. Choose the load pattern name, or the global direction of ground acceleration, depending on the type of load. See Applying Acceleration Loads for more information.
- Scale Factor. Enter a scale factor that multiplies the load before adding it to other loads applied. The buckling factor computed during buckling analysis will be with respect to the magnitude of the applied loads. For example, if you scale all the applied loads by a factor of ten, the buckling factor will be ten times smaller than if you had scaled the loads by a factor of one.
- - Add button. To add a load to the set of applied loads, enter the load type, load name, and scale factor at the top of the table, then click the Add button.
  - Delete. To remove a load from the set of applied loads, click on the load in the table to select it, then click the Delete button.
Number of Buckling Modes. Enter the number of buckling modes to be computed. We recommend that you compute three or more modes, since the buckling factor for the first few modes may not be very different.
Eigenvalue Convergence Tolerance. Calculation of buckling modes is an iterative process. Enter a relative tolerance to be used to determine when the eigenvalue (buckling factor) has converged. The default value is usually adequate.