Question regarding aluminum design manual 2020

[Bammer25]

I hate this code but have to use it for this case. Section H2.2 for torsion says the torsional strength is Fs*C where C is the torsional shear constant (with no context). I immediately think in terms of inches to the fourth power, but that gives a torsion of lbf*ft^2 which is not correct.

Does anyone know this formula to get in terms of inches to the third power?

 

[1503-44]

I don't know that code.
Some context of what you are trying to do would help.
Anyway try this and see if one of these fits your situation.

Torsional Constant
And
Torsional Shear Constant.

http://dir.cisc-icca.ca/files/technical/techdocs/updates/torsionprop.pdf

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[jjl317]

Assuming rectangular tubes? Check Part II / Chapter H of the Commentary Section (at least it's defined there in the 2010 ADM). See below

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1729767367/tips/ADM_eng_tips_102424_nddss7.pdf[/url]

 

[Bammer25]

Ahh thank you!

 

[jjl317]

No prob - the organization of the ADM can be annoying - this is a perfect example - the definition of C should be in the main text, not the commentary