Pin Connection - Slotted Hole
Pin Connection - Slotted Hole
(OP)
I have a situation where I need to be certain that a beam has a pinned and not a moment connection. It's a clip angle with a two bolt connection to a beam and 2 adhesive anchors to a concrete wall. The adhesive anchors can't take the full moment.
I wish to horizontally slot the top bolt hole to ensure a pinned connection. Has anyone done this with good/bad results?
Thanks
I wish to horizontally slot the top bolt hole to ensure a pinned connection. Has anyone done this with good/bad results?
Thanks






RE: Pin Connection - Slotted Hole
Dave
Thaidavid
RE: Pin Connection - Slotted Hole
RE: Pin Connection - Slotted Hole
When I've had the same concern, I've bolted a plate to the concrete and then used clip angles with three sides welds to connect the beam to that plate.
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: Pin Connection - Slotted Hole
That's a good idea too. I may have to see which one the fabricator prefers because they get all whiny when it's not a typical detail they use.
RE: Pin Connection - Slotted Hole
RE: Pin Connection - Slotted Hole
Also, the pinned connection with the angle welded to the supporting member and bolted to the supported member is fairly flexible because of the small return at the top of the angle. I'm not sure how flexible an angle with two adhesive anchors is compared to the welded angle.
It can take maybe half the moment. If something simple like a slotted hole can alleviate most of the moment, I'd like to do it.
RE: Pin Connection - Slotted Hole
Can you adjust your anchor detail to give yourself some more wiggle room with the potential moment?
RE: Pin Connection - Slotted Hole
First, the angle of rotation is very small so the bolts shouldn't really come do what youre saying very much.
Second, the forces are all vertical so per the code the slots must be perpendicular to the force, which they wouldn't be if I inclined the slots.
No, the reason they don't work is because the concrete edge distance is only 3-5/8" for the top anchor. Pullout is an issue. And they're post installed plus we are just a sub so I can't reinforce the anchors. Another option is seated angle support but then I'd need brackets near the top to prevent rotation which is a pain.
RE: Pin Connection - Slotted Hole
RE: Pin Connection - Slotted Hole
The short slot on the bottom is to allow for usual fit-up tolerances - just like any normally fit steel-to-steel connection. The long slot allows for that, plus the hoped-for rotation.
Dave
Thaidavid
RE: Pin Connection - Slotted Hole
It's late and I've had a long day so maybe I'm not following, but why do you need brackets to prevent rotation? I thought you were trying to achieve a near true pinned connection?
RE: Pin Connection - Slotted Hole
RE: Pin Connection - Slotted Hole
Cold beer helps with the long day...not sure reading eng-tips late at night helps much, although it's interesting following a few eng-tips heavyweights debate long-term concrete deflections!
RE: Pin Connection - Slotted Hole
1. Bolting near the neutral axis should reduce translation at the bolts
2. Excluding thread's at the shear plane improves ease of rotation
3. Welding aluminum reduces its strength significantly
4. I would think that 2 short slotted holes would be better than 1 standard and 1 long
5. Old connections with rivets had bolts staggered at the clip angle to reduce eccentricity. The beam side bolts should be higher than the support side. I believe that bolt offsets were 1 3/4" vs 2 1/2"
6. Is there space to use an L8 with 4 small adhesive anchors?
7. The seated connection sounds like a good alternative because it's symmetric, but wouldn't the top stability piece create the same problems with moment.
RE: Pin Connection - Slotted Hole
RE: Pin Connection - Slotted Hole