Torsion of a T section
Torsion of a T section
(OP)
I'd like to first get confirmation of a torsion question.
1) The shear center is located at the intersection of the flange and web. So if the load is applied at the end of the flange the torque is load x flange width/2?
2) The maximum shear stress is located at a point most distant from the shear center? So if both legs are 2" long then the maximum shear stress will be at the end of the web?
3) If 2 is correct then how can you increase the torsional capacity of the T section?
Thanks for any assistance you can provide.
1) The shear center is located at the intersection of the flange and web. So if the load is applied at the end of the flange the torque is load x flange width/2?
2) The maximum shear stress is located at a point most distant from the shear center? So if both legs are 2" long then the maximum shear stress will be at the end of the web?
3) If 2 is correct then how can you increase the torsional capacity of the T section?
Thanks for any assistance you can provide.






RE: Torsion of a T section
RE: Torsion of a T section
RE: Torsion of a T section
the standard formula for maximum stress = 3*T/(b^2*t) (i think) would suggest increasing the summed length of the elements of the X-scetion ("b")
Quando Omni Flunkus Moritati
RE: Torsion of a T section
Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin
RE: Torsion of a T section
The best way to increase the torsional capacity of a tee without increasing its overall dimensions is to add a couple of plates such that they form a triangle with the flange of the tee resulting in a closed shape. Better still, a pair of angles such that they form a box section with the flange of the tee.
BA
RE: Torsion of a T section
- support of granite slabs over a pool gutter drain
- stainless steel plates are being used to fabricate a section
- therefore, I wish to minimize the plate sectional area as well as the amount of welding required
- An HSS would be ideal, but the costs would be prohibitive
Maximum Torsional stress = Torque * y / J
For flat plates J = 1/3 ∑ bt^3
I'm using Roarke's formula to get an exact figure for the b/t ratio.
So given the above, what is the maximum shear stress due to torsion?
I've seen that y = simply the minimum thickness of the flange or web. Is this true or is y the distance to most extreme point in the section?
Also, is there a better way to use 2 plates to minimize the effect of torsion?
Thanks.
RE: Torsion of a T section
RE: Torsion of a T section
RE: Torsion of a T section
BA
RE: Torsion of a T section
RE: Torsion of a T section
BA
RE: Torsion of a T section
RE: Torsion of a T section
@ Hokie, Yes the granite is embedded into the lathe, but is supported by the stainless steel T section. The lathe does not provide any real support. Why wouldn't there be any torsion in the T? The whole section would try and rotate if a person were to jump on one side of the support. Am I missing something?
I agree at the ends the torsion can be ignored as the concrete and connection can absorb any twisting.
RE: Torsion of a T section
So are you saying that the granite pavers span between the tee sections? If so, the only way for the tee to be subject to twisting is for the granite to break/crack.
RE: Torsion of a T section
So if there is no need to check for torsion, all I need to check is the rotation of the section?
RE: Torsion of a T section
BA
RE: Torsion of a T section
I already suggested to use 1'-6" or 2'-0" width slabs and this would not be an issue, however the company wants/insists to have the design like this.
RE: Torsion of a T section
BA
RE: Torsion of a T section
For instance, there really is no need to insist on stainless steel. If they just eliminate stainless from the equation then a simple 2x2 galv HSS would be so easy to use.
RE: Torsion of a T section
BA
RE: Torsion of a T section
RE: Torsion of a T section
I've also already informed them of the case where the owner fails to maintain the pool and the stones start to move. This will be in the warnings in my notes. They actually wanted to go with 24" spacing and this is when I told them about the potential lawsuits.
RE: Torsion of a T section
The lathe below would provide enough support to keep the tiles from moving, that is until frost eventually breaks this bond. The joints are also caulked except on the right side of the section allowing excess water to drain into the gutter.
Ground or poured concrete is below on the left of the section, there is no cantilevered conditions, so this is not a concern.
All the tiles, except over the gutter, are on solid ground/concrete. Caulking, plus the mesh and lathe bonds the base of the stones.
There will still be twisting of the T, so if the company still insists with their detail, I'll just simplify the detail and use 2 vertical plates spaced apart, increasing the resistance.