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Method to obtain Torsion Constant (structural) 
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#1
Jan1910, 08:30 AM

P: 79

Hi every one.
I just wonder whether using Ix+Iy = J is a suitable method to calculate the Torsion Constant of a plate girders (full penetration butt weld at connection section) Since, as stated at wiki, the polar moment of inertia is only identical to J for circle tube and rod. p.s. is there any software/calculation method that i can obtain the J and Ixx,Iyy immediately. Thanks for your kind help in advence. 


#2
Jan1910, 10:16 AM

Sci Advisor
HW Helper
P: 2,124

No, J = Ix + Iy is not suitable, in this case. In this case, torsional constant (sometimes called K, instead of J) is K = (1/3)*summation(b*t^3), where b = length of each plate component in the cross section, and t = thickness of each plate component.



#3
Jan1910, 11:31 AM

P: 79

But i think that's for opened thin tube. The J that I would like to find is as attached. Btw, could you suggest some notable book name/website that I can refer to ? Thanks again for your kind assistance. 


#4
Jan1910, 01:11 PM

Sci Advisor
HW Helper
P: 2,124

Method to obtain Torsion Constant (structural)
Due to post 1, I thought your cross section was open, but now from post 3 I see it is not. I do not have an accurate formula now.



#5
Jan2010, 05:30 AM

P: 79

I wonder what books/ Software I should find to obtain the J? 


#6
Sep1710, 11:03 PM

P: 1




#7
Sep1810, 08:25 AM

P: 24

i did a search for "Solidworks torsion constant" to see if there was a way to do it with solidworks/addins. i didn't find a way to do it with solidworks but the first hit is to another forum where they discuss it including many programs others have used for that purpose. i don't know if the moderators care if i link to another forum so i will let you find it with that search.
also it seems that the BathoBredt theory could be helpful. i don't have the resources or know how to help with that though. there is a google books link that talks about it (5.6 and beyond): http://books.google.com/books?id=hGt...page&q&f=false another also, i have access to the book: Advanced Applied Stress Analysis by C.T.F. Ross; it talks about the torsional constant and bathobredt theory. 


#8
Sep1910, 01:59 AM

Sci Advisor
HW Helper
P: 2,124

Nice find, Lazer57. Su Solberg, if you post the dimensions of your cross section, we could play around with it, and try the BredtBatho formula.



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