simple shear connections
simple shear connections
(OP)
Steel beam framing to another beam with a typical shear tab and 1 row of bolts in ssl holes. Where the end of the beam is at a concrete wall, it is connected to the wall with an embed plate and welded shear plate also with 1 row of bolt in ssl holes.
I have a reviewer telling me that these support connections should be considered fixed and the bolts designed for the reaction moment. I said I typically assume this as simply supported with a simple shear connection and I only design for the reaction shear and the eccentricity moment. I believe both conditions are more of a flexible type connection than rigid. Who is right?
I have a reviewer telling me that these support connections should be considered fixed and the bolts designed for the reaction moment. I said I typically assume this as simply supported with a simple shear connection and I only design for the reaction shear and the eccentricity moment. I believe both conditions are more of a flexible type connection than rigid. Who is right?






RE: simple shear connections
You could bracket the reaction by computing both fixed and pinned conditions.
RE: simple shear connections
The problem is that the structure is already built and modeling the beams as fixed, the connections cannot accommodate the reaction moment without a substantial re-work. Even swapping the bolts with A490 would still not be enough and I cannot do a double shear connection due to the owner's preference for the structure to be removable.
One thing I was told when the structure is loaded, they would notice the deflection on the longest beam that approximates the result on my beam model for a simply supported beam. For me this is a confirmation that the beam is behaving closer to a pin connected beam rather than fixed.
I'm confident that the connections are OK, I really just need some ammunition to make the reviewer agree with me.
RE: simple shear connections
BA
RE: simple shear connections
How to deal with your reviewer will very much depend on what their particular concern is. Here are some ideas:
1) Support for a pinned connection.
- Flanges not connected.
- SSL holes might facilitate beam rotation.
- Your connection plate might yield in flexure before you develop the beam capacity.
2) Support for a fixed connection.
- If you have significant shear, your SSL holes might bind up (Link).
- The tolerance provided by the SSL bolt holes might actually be exhausted in situ.
- Pretensioned bolts may tend to act like slip critical bolts in service.
I'd have some ready answers to all of these questions before you make your pitch.
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: simple shear connections
The reviewer's concern is with a fixed beam model, the reaction moment resolved into horizontal shear would over-stress the bolts to failure. About the ssl holes binding up, I think it's a non-issue here as the connections only have 2 bolts. I'm guessing that's more likely to occur in a long row of bolts.
RE: simple shear connections
As for your ammunition, on page 10-4 of the 13th ed. it states that "The simple shear connections shown in this Manual are suitable to accommodate the end rotations required per AISC Specification Section J1.2."
I'm thinking that if your simple shear connection is comprised of the parts listed in the single-plate connections tables in the code then you've got what you need. Alternatively, if you want to get more theoretical you can calculate the rotation BAretired suggested and verify it matches with the code commentary required rotation for a simple shear connection.
RE: simple shear connections
If your bolt failure mode is bearing rather than shear, as I would expect, you could also argue that mechanism is self limiting and would effectively create the required pin.
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: simple shear connections
it's probably not the best time to review a design ... after it's been built !
another day in paradise, or is paradise one day closer ?
RE: simple shear connections
I'm thinking as long as the ssl hole tolerance per AISC is met, I don't have to worry about that scenario.
RE: simple shear connections
RE: simple shear connections
RE: simple shear connections