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

I am using STAAD to perform steel design on a member per the AISC ASD code. I want the column to be designed based on an unbraced length of 20 ft. I have set the UNT and UNB values to 20 ft, but STAAD appears to consider only a 10 feet length in its KL/r calculations. How do I correct this problem?

The parameters UNT and UNB are for specifying the unsupported length of the compression flange for the purpose of computing allowable stresses in bending compression.

If you want to specify the unbraced length for the purpose of computing allowable stresses inaxial compression, use the parameters LY and LZ. See Table 1 of the STAAD.Pro Help section Design > D. Design Codes > D1. American Codes > D1.B. American Codes - Steel Design per AISC 9th Edition > D1.B.1 Working Stress Design > D1.B.1.2 Design Parameters for details.