Members Subject to Flexure and Axial Force

[2457F]

Can anyone refer me to a technical publication that will demonstrate the derivation of equation H1-1a in the 14 edition of the AISC manual. I'd like to know where the 8/9 value came from. Chapter H of the book discusses it some but not in enough detail.

 

[271828]

I'm not at the office at the moment, but remember that the background is in Salmon and Johnson and / or the SSRC Guide to Stability Design Criteria for Metal Structures.

 

[ZeroExperience]

From the following book

http://www.amazon.com/Steel-Design-William-T-Segui/dp/0495244716

"Two formulas are given in the Specfiication: one for small axial load (AISC Eq. H1-1a) and one for large axial load(AISC Eq. H1-1b). If the axial load is small, the axial load term is reduced. For large axial load, the bending term is slightly reduced."

I believe the 8/9 term is a term they felt comfortable when reducing the bending term.

 

[271828]

ZeroExperience, surely even given your screen name, you can do better than that! LOL, just giving you a hard time.

The references I listed go much deeper than that. The basic idea is that a researcher performed a whole bunch of computerized, nonlinear spread-of-plasticity analyses on a specific beam-column. Axial loads varied from very small to large. Plot the results and one gets a figure that looks about like the bilinear curve one would get from plotting Eq. H1-1a and b. The thing I don't remember is how one goes from that to being able to use H1-1 with LTB, etc.