WF Torsion Question
WF Torsion Question
(OP)
For the attached configuration, I am looking at 2 options to support a girder at a WF beam location. Vertical cover plates will be added between the flanges to make a more torsionally resistant box section. The question I have is, does the magnitude of the torsion vary depending on if a top mount hanger is used vs. a bearing seat bracket welded to the web? In the attached drawing, the distance from the centroid of the beam to the centroid of girder bearing is the same leading me to believe the magnitude of torsion is equal. However, I "think" there may be more torsion when the load is hung from the top flange. Can't quantify this in my head though if there is in fact a difference.






RE: WF Torsion Question
RE: WF Torsion Question
Mike McCann, PE, SE (WA)
RE: WF Torsion Question
BA
RE: WF Torsion Question
1) Welding side plates onto your wide flange beam to make an HSS will cost a bundle. You're much better off detailing the torsion away as other here have suggested.
2) Remember that, whatever you do to improve the torsional capacity of your wide flange, the solution will only be as good as the connections at the ends of your beam. Standard beam connections are generally not appropriate for torsion.
In the past, I've used top flange hangers as you have in combination with a strap tying the bottom flange of the steel beam to the side of the girder. Again, this just turns wide flange torsion into girder bending. Of course, if your application is exposed, that's not likely to fly and you should consider something sexier like Mike's proposal.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: WF Torsion Question
Dik
RE: WF Torsion Question
BA
RE: WF Torsion Question
ENJOYING RETIREMENT......
RE: WF Torsion Question
Mike McCann, PE, SE (WA)
RE: WF Torsion Question
Dik
RE: WF Torsion Question
RE: WF Torsion Question
RE: WF Torsion Question
I don't understand what you are suggesting. How does a "kicker" remove torsion from a spandrel beam?
BA
RE: WF Torsion Question
There's some good information here, which formed the basis of AISC Design Guide 22
http://www.modernsteel.com/Uploads/Issues/December...
RE: WF Torsion Question
The simplest way to remove torsion in this case is to rotationally fix the WF to the end of the LVL girder, or effectively ensure the LVL spans to the center of the WF.
BA