Massive HSS Beam Torsion and Moment Connection connecting into smaller W-Beam Web (EIT) 13

[onlym112]

Hello,

I am currently designing a connection where I have an HSS356x254x13 long side vertical into a W310x45 beam which bear on top of a W200x36 Column. This connection is a moment and torsion connection where the torsion is 50 kNm and moment is 60 kNm. I am having a hard time picturing how I will connect this and was wondering if anyone could give me their insight. I have sketched two possibilities however one of them will not work due to a lack of weld access. Please see the pictures of the model and my sketch below.

I also considered an endplate option but I am not allowed to portrude my endplate proud at the top to fit my 1" tension bolts. Also there isn't much guidance on a endplate HSS moment connection and based on the HSS size, things can get real ugly and I am not too sure how to handle it. Can anyone give me some feedback? Thank you very much

 

[KootK]

See below for a rough sketch on how I'd try to approach this.

Love the detail, both in terms of the concept and the generosity involved in developing and posting it. Mildly annoying in that it robs me of the opportunity to post a sexy, thread crushing detail of my own but whatever.

t feels like that long, brown girder should be pulling in a lot of the canopy load and leaving those HSS box girders alone in regards to torsion. UNLESS the system is over restrained and the model is revealing that the torsional stiffness of the HSS is greater than the flexural stiffness of the brown girder. Then the HSS may be reaching out and picking up the girder (which wouldn't be wonderful) and resulting in alot of torsion. Am I seeing that right?

That's exactly how I see it. The brown girder must just be pushing L/d too hard to be effective.

 

[KootK]

I don't believe that the discussion about this nutty connection can be meaningfully separated from an open discussion about how lousy the framing layout is. Yeah, there is some risk in that we don't know 100% of the context here but, at the same time, I feel 90% sure that this is just crap EOR work. In one respect, I'm 99% sure that this is crap EOR work. At the location of the blue dot below, there should be a connection that transmogrifies the torsion in the tube into flexure in the grey beam. This would make it such that the connection at the purple dot would only need to be detailed to transfer strong axis moment across the column to the cantilever on the other side.

This situation is such an egregious example of EOR incompetence that I feel that OP might actually benefit from submitting a query to see if this change could be made rather than just eating the EOR's original connection loads. It should be a super easy sell if the incompetent EOR has a competent supervisor somewhere up the food chain. If someone working under my direction came to me with an RFI suggesting this change, my response would be: Hell yes dumbass! Whomever this connection engineer is, make sure she gets a Christmas card and bottle of Glenfiddich this year. Pending some kind of training, you are henceforth forbidden from using FEM software. Fool! Please don't quit (I prefer to fire on my own terms).

Obviously, the calculus of whether or not the effort of the RFI justifies the improvement to the connection is a question that only OP can answer. That said, I feel that it's entirely plausible that the the benefit of that exercise might justify the associated hassle.

 

[hokie66]

CANPRO,

Others have pointed out the problems here. If the structural design drawings are nonsensical, detailing connections to comply with nonsensical instructions won’t solve the problem. Sorry to offend your sensibilities about delegated design.

 

[271828]

This situation is such an egregious example of EOR incompetence that I feel that OP might actually benefit from submitting a query to see if this change could be made rather than just eating the EOR's original connection loads. It should be a super easy sell if the incompetent EOR has a competent supervisor somewhere up the food chain. If someone working under my direction came to me with an RFI suggesting this change, my response would be: Hell yes dumbass! Whomever this connection engineer is, make sure she gets a Christmas card and bottle of Glenfiddich this year. Pending some kind of training, you are henceforth forbidden from using FEM software. Fool! Please don't quit (I prefer to fire on my own terms).

I think that is a great idea.

Also, thanks for the Saturday morning laugh!

onlym112, you might frame the RFI as "can we replace the W310 with a deeper beam" that would make the connection easier. The EOR might be able to make that call without spending any time, so your chances might be better. Almost every time we've asked for that, we've gotten a yes. I think EORs are typically so busy that any time required to study and recalc often leads to a no.

 

[KootK]

Alright, it took 48 hrs and two long showers to work out something competitive but here's mine. It's a lot of connection for one joint but I feel that it might be worth that given:

a) The simplifications that result in those connections and;

b) The rather robust transfer of the various loads involved.

c) All of the field connections are just run of the mill bolted moment connections. No gymnastics.

If one were willing to do some field welding, this could likely also be done without making a stub of the W310x45 at the joint. That said, I suspect that arrangement would have to consider some tolerance issues that the sketched detail circumvents conveniently.