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RE: ASD9 Chapter K

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While checking a beam for sidesway web buckling 
> (Section K1.5), I noticed that 
> eqns K1-6 and K1-7 do not include Fsuby. 
> If you calculate the equations as 
> shown, you end up with a in^2 unit, not kips 
> as I would expect. I'm assuming 
> that the 6800 value must have a ksi unit but 
> wouldn't the limits vary based 
> upon a 36 ksi vs 50 ksi yield stress or is this 
> already factored in? Chapter 
> K of the LRFD spec's is similar.
 
Sidesway web buckling is a stiffness-based criteria, so the yield strength of the steel does not affect it.
 
Sidesway web buckling is treated more generally and accurately in the 1993 LRFD Specification. Specifically, the effects of the flexural load level in the beam to which the limit state is applied is considered. For a large moment (i.e., a moment greater than the yield moment), there is a reduction in the local strength to resist sidesway web buckling. In LRFD, this means a moment greater than FySx. In ASD, the corresponding limit above which a similar reduction would apply is 0.6FySx.
 
Charlie