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Steel Design Sanity Check

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I’ve run across several instances where according to ASD (9th ed), I have an existing built-up column or girder that has a flange that is a slender element (thanks to kc) and a web that is noncompact.  As far as I understand it, in this situation, I’d have to calculate the effective flange width and then recalculate section properties based upon this reduced flange width.  But if I look at LRFD (3rd ed), I find that my flange is noncompact and my web is noncompact.  I check my allowable bending stresses (ASD) and I’m allowed something like 20 ksi (fully braced).

 

I switched codes because 1) I feel that the beam does not know which code I’m using and I that LRFD is newer and probably more accurate in terms of slenderness calcs. 2) My boss does NOT want me using LRFD for beam calcs because he is a ‘psi guy’. 3) I’m a little intimidated by things like X1, and X2 if it’s not simply given to me. and 4) In the end, I’d have to factor up my loads and do an LRFD calculation, which would not tell me the allowable stress. 

 

It may be a moot point when we finally get our new ASD/LRFD manual and start using it, but is this a wrong way to do this?  What have other people done when they’ve encountered this problem?

 

Brian S Bossley, PE

Ventura Engineering

7610 Olentangy River Rd

Columbus, OH 43235