Load Case Data Form

Additional form:  Design Load Type

Before defining load cases, define any load patterns or functions that will be needed; see the Define Load Patterns topic for more information.

• Load Case Name. Accept the default or enter a name for the load case being defined. It should be unique among all load cases of all types.

• Load Case Type drop-down list. ETABS accommodates many types of load cases. Most broadly, analyses are classified as linear or nonlinear, depending on how the structure responds to the loading. Select the primary load case type, then select the available Subtype (e.g., Linear or Nonlinear). These options will be different for different load case types.

• Mass Source drop-down list. Click this drop-down list to select the mass source to use for the load case being defined. Typically this will be set to the default mass source and not editable. A drop-down list showing other defined mass sources will only be available if the Load Case Type is set to Nonlinear Static, to Nonlinear Staged Construction, or to Time History - Nonlinear Direct Integration.

• Notes button. Click this button to access the Load Case Notes form. Use that form to add Notes about the load case to the model file.

• Design button. Click this button to access the Design Load Type form. Choose Program Determined, or User-Defined. If user-defined is chosen, select a load pattern from the drop-down list; the selected load pattern will be used in the load case. The specified load case design types are used in creating automatic design load combinations.

The remaining data on the form depends on the chosen type of load case. Click on the appropriate link for the type of load you are defining:

Note: For modal cases, please refer to Modal Cases

• Static:

• 1. • Linear Static. The most common type of analysis. Loads are applied without dynamical effects.

     • Nonlinear Static. Loads are applied without dynamical effects. May be used for cable analysis, pushover analysis, and other types of nonlinear problems.

     • Nonlinear Staged Construction. The definition of a nonlinear direct-integration time-history load case for staged construction.

• Response Spectrum. Statistical calculation of the response caused by acceleration loads. Requires response-spectrum functions.

• Time History:

• 1. • Time History.  Time-varying loads are applied. Requires time-history functions. The solution may be by modal superposition or direct integration methods.

     • • Linear Modal

       • Linear Direct Integration

     • Nonlinear Time History.  Time-varying loads are applied. Requires time-history functions. The solution may be by modal superposition or direct integration methods.

     • • Nonlinear Modal

       • Nonlinear Direct Integration

• Buckling. Calculation of buckling modes under the application of loads.

• Hyperstatic. A hyperstatic load case is required in certain codes when performing design with post-tensioning. Reactions from the specified Base Case linear load case are applied to a modified model where the supports have been removed.

Access the Load Case Data form as follows:

1. Click the Define menu > Load Cases command to access the Load Cases form.

   • Click the Add New Case button.

   • Highlight a previously defined case and click the Add Copy of Case, or Modify/Show Case button.