Load Combinations

Forms: Load Combinations, Add Default Design Combos, Convert Combos to Nonlinear Static

Program design is based on a set of loading combinations. In ETABS, load combinations, or combos, are generated automatically by the program or are user defined. If the automatically generated load combinations are acceptable (note that these combos are created/recreated after each design run), no definition of additional load combinations is required.

Use the Design menu > {Type} Design > Select Design Combinations command to work with automatic load combinations.

Use the Define menu > Load Combinations command to specify user-defined combinations, Add Default Design Combos, or Convert Combos to Nonlinear Cases.

Automatic and user-defined combination may be used simultaneously for design. Note that each time a design is run, the automatic combos are regenerated, thereby replacing any previous automatic combos. User-defined combinations are not changed during design.

Note: The Design menu command must be used to select the user-defined combinations to be used in design, regardless of whether the combos were created manually or the default design combinations were added using the Define menu. The program automatically selects the automatic code-generated combos (generated after each design run).

Note: Notional loads are not included in automatic combinations. Thus, to consider the combination of notional and lateral loads, appropriate User Load Combinations should be generated.

Manually Create User-Defined Load Combination

Click the Define menu > Load Combinations command to access the Load Combinations form.
Use the following buttons on that form to complete the appropriate action.
- Add New Combo button. Click this button to display the Load Combination Data form and manually create a user-defined load combination for the model.
- Add Copy of Combo button. Use this button to add a new definition based on an existing combination.
- 1. Select the load combination to be copied in the Load Combinations display area.
  2. Click the Modify/Show Combo button to access the Load Combinations form.
  3. Make any necessary adjustments using the options on the form.
  4. Click the OK button to return to the Load Combinations form. Then click the OK button on that form to close it.

- Modify/Show Combo button. Use this button to modify an existing combo without adding a new combination.
- 1. Select the load combination to be modified in the Load Combinations display area.
  2. Click the Modify/Show Combo button to access the Load Combinations form.
  3. Make the necessary adjustments using the options on the form.
  4. Click the OK button to return to the Load Combinations form. Then click the OK button on that form to close it.
- Delete Combo button. Use this button to delete a combo.
- 1. Select the load combination to be deleted in the Load Combinations display area.
  2. Click the Delete Combo button.

- Add Default Design Combos button.
- 1. Click the Add Default Design Combos button to display the Add Default Design Combinations form.
  2. Select the design type (e.g., steel frame, concrete frame, aluminum frame, cold-formed steel frame).
  3. The program will add load combinations in accordance with the code selected using the Design menu > {Type} Design > View/Revise Preferences command and will then redisplay the Load Combinations form with the code-generated combinations shown in the Load Combinations display list.,
- Convert Combos to Nonlinear Cases button. Use this button to immediately convert the selected combinations to new nonlinear load cases.

Note: When using the Add Default Design Combos button or the Convert Combos to Nonlinear Cases button, multiple combinations can be selected in the Combinations display list using standard Windows selection techniques (e.g., drag the mouse over multiple combinations in the list; hold down the Ctrl key on the keyboard and click the mouse to make "random" selections).