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Re: strong axis bending of a bar

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I don't know where you got that formula, but I'll take a shot at trying to figure out the appropriate stress within AISC.  The allowable bending stress for a plate bent about its strong axis has to be found in:
 
Chapter F - Beams and Other Flexural Members.
 
F1 - I-shaped members and channels.
F2 - weak axis bending.
F4 - shear stress.
F5 - stiffeners.
F6 - built-up members.
F7 - web-tapered members.
 
Clearly none of these sections apply, so it must be:
 
F3- Allowable Stress:  Bending of Box Members, Rectangular Tubes and Circular Tubes.
 
Possibly AISC considers a plate bent about its strong axis as a special case of box or rectangular tube.  Within F3 the allowable flexural stress will be either 0.6Fy or 0.66Fy, depending on lateral support.
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John P. Riley, PE, SE
Riley Engineering
20 Oakwood Drive, Blue Grass, Iowa 52726
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I think this is an easy one but I haven't found it yet.  I have written in my AISC 9th edition that the allowable bending stress of a plate bent about its strong axis is Fb = 10,000/ (Ld/(t cubed)) <.66Fy.  Anybody know where I got this?  Is it correct?  Is it in the AISC spec?  I know that .75Fy is good for the weak axis bending.  Thanks for your help.

Kenneth S. Peoples, P. E.
Lehigh Valley Technical Associates
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Northampton, PA 18067-9039
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e-mail: kpeoples(--nospam--at)lvta.net