How to calculate J and Cw for non-standard shapes?
How to calculate J and Cw for non-standard shapes?
(OP)
I have an inverted "T" shape and I need to calculate the J and Cw values. I donot have quick access to the Roark Book, as I understand it is in there. Does anyone know how to do this?





RE: How to calculate J and Cw for non-standard shapes?
b = width of the flange
tf = thickness of the flange
h = height from the tip of the stem to the mid-height of the flange (d - tf/2)
tw = thickness of the stem
J = 1/3 x ((b x tf^3) + (h x tw^3))
Cw = 1/36 x ((b^3 x tf^3)/4 + (h^3 x tw^3))
So a verification -
Let b = 4
tf = .5
h = 6.25
tw = .3
Then I get J = 0.2229
Cw = 0.2387
Cw = 0 for small thicknesses
RE: How to calculate J and Cw for non-standard shapes?
Is a "T" value valid for an inverted T?
Also, I thought the values depended on a "mesh", or matrix...?
Guess I really don't understand how these values are derived.
RE: How to calculate J and Cw for non-standard shapes?
RE: How to calculate J and Cw for non-standard shapes?
RE: How to calculate J and Cw for non-standard shapes?
Now if you try the same thing with a T-section, there is no opposite flange to create the couple that can carry the torsion. Even with your beefy section, the warping will be a small effect.
RE: How to calculate J and Cw for non-standard shapes?
RE: How to calculate J and Cw for non-standard shapes?
RE: How to calculate J and Cw for non-standard shapes?
RE: How to calculate J and Cw for non-standard shapes?
I find all the given formulae for various shapes fine and dandy, however I would like somthing more along the lines of a derivation.