non-circular torsional stress

[metman]

In strength of materials text by Singer for torsional shearing stress of a rectangular section:

Ss = (T/ab2)[3 + 1.8(b/a)]
Where T = Torque or torsional load
a = long side and b = short side of the rectangular section

I have a symmetrical built-up section – and therefore not solid. Can I simply calc
Ss = Ss1 – Ss2 where
Ss1 = stress on large area and
Ss2 = stress on small area?

Thanks for any input.


Design for RELIABILITY, manufacturability, and maintainability

 

[Bagman2524]

It should be checked as a solid section and you have to check all welds used to make the built up member to ensure they can handle the stresses

 

[prex]

Not sure to understand you correctly: what do you mean by 'large area' and 'small area'?
For the torsional modulus of a built-up I section look here.

prex
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[pbc825]

No.

Is the section opened or closed? Please post the cross section, material of construction, as well as the restraints and loads. All are important. I'll help you, but we need to narrow the field first.