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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.
John P. Riley, PE, SE
Riley Engineering
20 Oakwood Drive, Blue Grass, Iowa 52726
Tel & Fax:  319-381-3949

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
1584 Weaversville Road
Northampton, PA 18067-9039
ph: 610-262-6345
fax: 610-262-8188
e-mail: kpeoples(--nospam--at)