Torsional Constant

[71corvette]

I'm trying to calculate the torsional constant "J" for a rectangular voided slab. The slab is rectangular with three voids located along its horizontal center.

Can I calculate the torsional constant for a solid rectangular section and simply subtract the sum of the torisional constants for the three voids?

 

[stanfea]

I think I would calculate the J value using the perimeter of the tube only. In that sense you are really only ignoring the vertical webs which likey would contribute little anyway. The formula for an open tube with different flange and sidewall thicknesses is in any standard mechanics of solids text. If you don't have it let me know.

Stan

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