Location of maximum shear stress for I section under torsion

[jgrady]

Does anybody have a reference for this? All I can find is for rectangular section which has maximum stress at the middle of the side edges of the rectangle and zero stress at the corners. What would be the maximum point to an I section? At the fillet between the web and flange?

Thanks in advance

 

[mike20793]

You may want to check out the AISC Design Guide for torsion (9 I think). They have good diagrams showing the stress distribution through the section.

 

[KootK]

I think that you'd have two components of shear stress involved:

1) St. Venant torsion stress. I'd expect the maximum stress to occur at the top and bottom of the flanges (assumed thicker than the web).

2) Warping torsion. Since the flanges act more or less as two independent plates flexing in plane, the max stress would occur at mid-width of the flange.

In a wide flange beam, warping torsion should dominate.

So I guess that my final answer would be that the max shear stress due to torsion would occur at top of the top flange and the bottom of the bottom flange, both at the centerline of the cross section.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.