Applies To
	Product(s):	STAAD.Pro
	Version(s):	All
	Environment:	N/A
	Area:	Steel Design
	Subarea:	General Steel Design Solutions
	Original Author:	Bentley Technical Support Group

How do I get a design parameter, say the RATIO parameter, to be applied only to certain load cases?

You would need to use the "LOAD LIST" command. For example, if you only were interested in the 1st, 3rd and 5th load cases for the RATIO parameter you would need to write:

LOAD LIST 1 3 5
RATIO 0.5

In your input file.