The Dynamics Options tab in the Modal Time History dialog box sets solution related options:
Start time: Starting solution time in seconds.
End time: Ending solution time in seconds
Time increment: Solution time increment. The limit on the total number of solution steps is 15000.
Multiplication factor: The factor that the dead loads are multiplied by.
For example, if you enter 2 for the multiplication factor, the results from the selected static study are multiplied by 2, and added to the dynamic study results at every solution step.
The results are valid only if they are within the linear stress range.