A. To add a change command

To add a change command which is required for performing a subsequent analysis command, use the following procedure.

A change command is only added after an analysis command.

In addition to being used for a new analysis, the change command is used to change the support conditions, active/inactive member status, load conditions, etc. The stiffness matrix being solved will be reset when a change command is used.

Either:

select the Analysis page

or
on the Analysis and Design ribbon tab, select the Analysis Commands tool in the Analysis Data group

The Analysis/Print Commands dialog opens.
Select the Change tab.
(Optional) Check the After Current option if you previously selected the analysis command in the input file list within the Analysis - Whole Structure dialog. This option allows you to specify specifically where the command is added. Otherwise it will be added to the end of the input file.
Click Add. The change command is added to the input file.

You can now add an additional analysis command to the input file. A change command with no subsequent analysis command has no effect.