Warping Constant of Back to Back Channels

[MagicFarmer]

So quite some time ago @tennist had a post asking for help calculating the Warping Constant (Cw) of back to back channels:

https://www.eng-tips.com/viewthread.cfm?qid=367554

I have used the equation cited, but also compared it to the formula out of Roark's Formulas for Stress and Strain (attached), and am getting vastly different numbers. I can see that the variables used in the formula in Roark's reference the centre of the flange/web of the channels. Has anyone else used the Roark's or @tennist's equations? In my case, Roark's produced a value of less than half of that of @tennist's equation.

As always, thanks in advance.

Regards,
MF

 

[prex]

Both formulae are identical, when t_f=t_w, so you should recheck your calculations. This sheet is based on the same formula, that you can visualize by entering Options->Show formulae in the menu

prex
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