Extended Endplate Shear Connections?
Extended Endplate Shear Connections?
(OP)
I have searched Google to no avail, so now I’m turning to the even more powerful eng-tips forum members.
We have been seeing a type of shear connection where the web of a tee is fitted perpendicular to a girder web and the connecting beam is bolted through the flange of the tee using an endplate. I guess the advantage to this is that the beam can be cut square and cut short. Additionally, no bolts are shared, so OSHA should be happy. Has AISC commented on these? The mechanism which provides end rotation flexibility is not intuitively obvious to me, and the apparent eccentricity hurts my eyes to look at.
I have used connections similar to these when have a column continuous through a girder (with their respective webs @ 90 degrees). I fit a tee to the girder web to provide a direct load path for the column flange load above into the column flange below through the outstanding tee flange. If a beam intersects at the same point, then it frames into the tee flange with standard clips.
These other connections I’m asking about are one-sided and are not at a column. The tee is simply to shorten the beam and to make the connection outside of the limits of the girder flanges. Has there been any discussion of these types of connections? I presume there has been. They seem to be somewhat common in parts of Europe.
We have been seeing a type of shear connection where the web of a tee is fitted perpendicular to a girder web and the connecting beam is bolted through the flange of the tee using an endplate. I guess the advantage to this is that the beam can be cut square and cut short. Additionally, no bolts are shared, so OSHA should be happy. Has AISC commented on these? The mechanism which provides end rotation flexibility is not intuitively obvious to me, and the apparent eccentricity hurts my eyes to look at.
I have used connections similar to these when have a column continuous through a girder (with their respective webs @ 90 degrees). I fit a tee to the girder web to provide a direct load path for the column flange load above into the column flange below through the outstanding tee flange. If a beam intersects at the same point, then it frames into the tee flange with standard clips.
These other connections I’m asking about are one-sided and are not at a column. The tee is simply to shorten the beam and to make the connection outside of the limits of the girder flanges. Has there been any discussion of these types of connections? I presume there has been. They seem to be somewhat common in parts of Europe.






RE: Extended Endplate Shear Connections?
Sketch, please!
RE: Extended Endplate Shear Connections?
I don't know of any specific AISC guidance but here are some contradictory thoughts:
1) You might get some rotational flexibility out of the tee flange in ending at the top.
2) If you could call the end plate connection a rigid-ish moment connection, perhaps the connection could be treated like an extended shear tab connection. I very much doubt this is what has been done however.
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.
RE: Extended Endplate Shear Connections?
http://www.larrymuir.com/Documents/Design%20of%20U...
RE: Extended Endplate Shear Connections?
By chance is this connection for a big industrial chemical facility?
RE: Extended Endplate Shear Connections?
RE: Extended Endplate Shear Connections?
RE: Extended Endplate Shear Connections?
RE: Extended Endplate Shear Connections?
RE: Extended Endplate Shear Connections?
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.
RE: Extended Endplate Shear Connections?
RE: Extended Endplate Shear Connections?
I am not advocating ignoring a possible problem; I'm just saying we should recognize that we've likely been facing and dealing with a similar issue all along.
RE: Extended Endplate Shear Connections?
If the original design engineer (Engineer of Record) and the connection engineer are the same, this can be worked out between the two. If they are different parties, the cooperation often is not there. The Engineer of Record will want just shear applied to the supporting beam, and the eccentric shear resolved through the connection.
RE: Extended Endplate Shear Connections?
RE: Extended Endplate Shear Connections?
Brad: Me too!
RE: Extended Endplate Shear Connections?
RE: Extended Endplate Shear Connections?
If these connections find their equalibrium without torsional checks, I would think any connection no matter how rigid could be deemed a shear connection. Or maybe I'm misunderstanding the deisgn process.
I'm a little surprised I can't find anything out there from AISC or others.
RE: Extended Endplate Shear Connections?
RE: Extended Endplate Shear Connections?
RE: Extended Endplate Shear Connections?
RE: Extended Endplate Shear Connections?
Out of interest I did a simple study to see the difference in the OP's case. I do not have much time right now to summarize this in more detail, but I thought I would post a few of the images for others and to see if there was any interest in looking at a few others. I know the von mises stress are not the best for the discussion, but they seem easier than a vast number of plots for the scope of this. I think there is merit to this connection detail for a fully automated plant. In addition to the savings in beam length it also seems very probable one will have more bolts than they would have with a shear tab. I would hope the steel companies will not suggest an asymmetric bolt pattern? For a plant that is not automated this detail seems more prone to fit problems.
RE: Extended Endplate Shear Connections?
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.
RE: Extended Endplate Shear Connections?
There are only two types of torsion: compatibility and stability. By "just...torsion" I assume you mean stability torsion. You don't have stability torsion in the OP's situation. The rotation doesn't have to be released by connection flexibility, but rather by supporting beam rotation. That is one of the most wonderful things about steel...it is ductile. Open steel shapes have little resistance to torsion, so they will rotate a lot with little change in stress state.
RE: Extended Endplate Shear Connections?
Compatibility torsion is that which can be redistributed through yielding. The rest is equilibrium torsion. Steel is generally only ductile at the material level. At the member level, many members will fail via some form of non-ductile buckling. The primary story of steel is the story of buckling, not yielding.
Many steel section are indeed flexible in torsion. But that just changes the torsion that member will attract. It doesn't mean that redistribution will occur. You're unlikely to ever plastify a wide flange girder in torsion. Rather, you'll induce some complex mode of buckling or simply tear apart your hapless girder end connections.
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.
RE: Extended Endplate Shear Connections?
RE: Extended Endplate Shear Connections?
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.
RE: Extended Endplate Shear Connections?
RE: Extended Endplate Shear Connections?
1) The distance between LTB brace points remains unchanged as the distance between supported beams.
2) The fixity of the brace points improves due to the increased torsional restraint provided by the supported beams. This benefit is less significant than it might first appear however. You gain some rotational restraint but do not gain true torsional fixity as warping strain is not restrained.
3) To achieve true torsion redistribution, something has to plastify. In this case, I think that's the flanges yielding inwards from the tips under warping. As the flanges yield, Iy and Cw drop fast and the likelihood of LTB buckling between beams increases.
When you add all that up, I'm not really sure what you get.
I'm really not all that concerned about buckling although I always enjoy debating the finer points of theory. The primary point that I've been trying to convey is that there generally is not girder torsion redistribution at work in steel systems as there often is in concrete systems except, perhaps, in the connections when they are made rotationally flexible. You wanted to know why steel folks care so much about connection rotation capacity. That's why.
You do a funny version of agreeing to disagree. I like it.
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.
RE: Extended Endplate Shear Connections?
RE: Extended Endplate Shear Connections?
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.
RE: Extended Endplate Shear Connections?