Single Web Stiffeners for Bearing? 2

[aknyfg]

Hi folks,

I've been presented with an issue on a job where the erector did not install the stiffeners as specified. Now a beam that is transferring a column can not be accessed to install a stiffener plate on one side (wall is in the way). I've been looking through the SCM and it seems that they are very specific on the word "pairs" for the stiffeners. The commentary does not seem to help either. Does the AISC not allow for use of a single stiffener for a concentrated compressive load? Does a single doubler plate make the most sense in this situation? Thanks

 

[BAretired]

Is the column a Wide flange with web aligning with the beam web? If so, stiffeners should align with the column flanges. I would think a "pair" of stiffeners refers to one each side of the beam web. To get one under each column flange, you would need two pairs.

If the stiffeners cannot be aligned with the column flanges, I don't think they will do much good. The Contractor may have to remove enough wall to permit placing stiffeners as detailed on the drawings.

BA

 

[aknyg]

I understand pair as both sides of the flange as well. It's important that I don't alter the neighboring wall. There's only about 2+/- inches of clear space so they'll have to remove a bit of it. It's an interior gravity column so I'm not worried about any couples, just a single concentrated compressive load. Although I'm not a fan, the AISC addresses double plate in the singular so I'm wondering if a single sided web doubler will be the best option here. From a mechanics perspective I don't see the issue of a single sided stiffener as long as the eccentricity from the centroid of the built up column is taken into account but I don't know if the AISC would prohibit it.

 

[KootK]

Is the column a Wide flange with web aligning with the beam web?

We can do a lot more to help if you provide an answer to this question aknyg.

Does the AISC not allow for use of a single stiffener for a concentrated compressive load?

To my knowledge, there is no prohibition on single stiffeners. The truth, which may not be particularly helpful, is that any connection arrangement is probably viable so long as you can demonstrate that it works by the numbers. The stiffeners may be performing a number of functions:

1) Keeping the beam web from crippling.
2) Keeping the beam web from buckling.
3) Keeping the beam web from sway buckling and, generally, stabilizing the joint.
4) Providing an appropriate bearing surface for the column.
5) Keeping the column web from crippling.

That said, with a web aligned wide flange column to wide flange beam connection, often the detailing is simply a result of a "standard detail" being applied to the connection. In that case, there is usually wiggle room for modifying the connection if you understand the critical failure modes.

Do you know which failure modes are critical here? If so, you may well be able to get away with one sided stiffeners.

Does a single doubler plate make the most sense in this situation?

Again, it depends which failure modes you're hoping to address by using the web doubler. Web doublers are normally used to address shear capacity and shear buckling, neither of which is likely to be an issue here. I supposed that the doubler could also be used to address ordinary beam web buckling however. No matter what, I'd retain the stiffeners on at least one side. Even one sided, they'll do a lot to stabilize the joint (item #3 above).


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.

 

[aknyg]

Crippling/Buckling

 

[KootK]

Crippling and buckling of what? Beam web? Column Web? Both?

Is the column a Wide flange with web aligning with the beam web?

Help us help you. Just type Y or N. Or, if you're feeling sporting, supply a sketch.

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.

 

[aknyfg]

Web of column is normal to beam web. Is it not clear that I'm talking about web crippling and buckling?

 

[hokie66]

No code is going to tell you all you need to know about transferring this column load through the beam with the webs normal to each other. How are the column flange loads to be transferred? How much load are you talking about? What are the column and beam sizes?

 

[aknyfg]

10x30 beam, and a w14 column. Don't have the specific load and column section on hand.

 

[hokie66]

W14X?? You need more information than just "put some stiffeners in the beam".

 

[KootK]

Is it not clear that I'm talking about web crippling and buckling?

I didn't ask whether or not you were talking about web crippling. I asked on which member is web crippling / web yielding critical? It could be the beam, the column, or both. I'm trying to narrow the scope of the problem in order to help you effectively, that's all.

I'd recommend reviewing this thread for ideas: Link. If a "do-nothing" solution doesn't calc out, consider a detail like the one shown below. It can be accomplished without demolishing any of the existing wall that you're trying to preserve.

I agree with BA's concern. A W10x30 is a small beam and a W14 can potentially be a very large column.

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.

 

[BUGGAR]

What does the erector propose to fix his error? You're not him are you? You are not answering questions.