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

While designing a few members as per AISC 9th edition code I am getting a message "THIS VERSION DOES NOT DESIGN PLATE GIRDER PER CHAPTER G WITH h/tw > 970 / sqrt(FY)". What does the message mean?

This message comes up when designing members with deep webs as per the AISC 9th edition code. The requirements of Chapter G(Plate Girders) - pages 5-51 through 5-53 of the AISC ASD 9th edition manual - are not implemented in STAAD – both past and present versions. AISC defines plate girders as I shaped sections made of plates with deep webs.

In STAAD.Pro 2006 and older, if h/tw of the web of a beam exceeded 970/sqrt(Fy), such members were designed in accordance with Chapter F and Appendix B of the code as beams with slender webs. The program never checked the member against the rules of Chapter G

In STAAD.Pro 2007, this check (to determine whether h/tw of a beam exceeds 970/sqrt(Fy) in accordance with Chapter G) has been implemented. So, if h/tw of a beam exceeds 970/sqrt(Fy), meaning that the beam is now a candidate for being designed as a plate girder, STAAD puts out this message. It does not design these beams.

One way to get around this limitation is to design the beam per the third edition LRFD code. In your input file, specify the commands

PARAMETERS
CODE LRFD

As an alternative, newer versions of the AISC code like AISC 360-05 or AISC 360-10 may also be used. Commands for each are provided next

AISC 360-05 :

CODE AISC UNIFIED 2005
METHOD ASD
...

AISC 360-10 :

CODE AISC UNIFIED 2010
METHOD ASD
...