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

Why is it that when I change the yield and/or ultimate strength of steel using FY and/or FU in the material definition, there is no effect on the steel design results?

The Fy and Fu properties in the material definition are used by the Connection Design module only.  They do not have any bearing whatsoever on the steel design results. 

FYI, the Fy and Fu properties in the material definition appear graphically as shown below:

 

In the input command file, these properties look like this:

If you wish to change the yield strength of steel for design within STAAD.pro, you must use the FYLD parameter as described in the following wiki:

Changing the Yield Strength of Steel