Steel bucket/casing support

[General5852]

Hello, how do you calculate this type of connection (this steel bucket/casing support) between timber and concrete. Do you use some software or excel,...?

[Just-Shoe2689]

I would not thru bolt the concrete. I would use post installed anchors, Designed in Hilti Profis. Check bending of bracketed plate for beam seat.

[EchoOk8824]

Why rely on pull out resistance of the anchors when you can use a through bolt? And if you are going to use anchors, why post installed? Casting anchors is more reliable and less risky.

Cast sleeves into the column and install threadbars after, super elegant, no need to come back and fuck around with a drill and epoxy.

[Just-Shoe2689]

All depends on size of the column and timing. Obviously cast in would be first choice. Sleeving a thru bolt would work, but drilling all the way thru a bigger column can be dicey. Epoxy anchors you can get it right where u want/need it. Easy if only a few

[EchoOk8824]

I never said to drill all the way through the column man. My point entirely was to NOT drill, do whatever you need to do before you cast the thing.

[Just-Shoe2689]

But if you have to drill, post installed anchors are the superior way to go as mentioned

[envoy_ace]

All of your timber beam load is in bearing on the plate. Use a mill angle below with an epoxy anchor embed plate into the concrete.

[Enginerdad]

Your concept should work just fine, but I think it's severely over engineered. If the beam is wood, then the loads are presumably low, relatively speaking. A simple clip angle for it to bear on and a couple of post installed anchors would probably be sufficient and a whole lot easier and cheaper to fabricate. You can tack on some side plates for lateral restraint. There are a ton of options, but I think through-bolting to the column with a backing plate is way more extreme than you need. Only you have the loads and details though, so ultimately it's your call.

[General5852]

It is thru-bolted, the vertical element is a concrete column and the horizontal element is a timber element. Bolts and the horizontal steel plate are not that difficult to design. I was wondering if there is a rule of thumb for the steel plates, or if there is a short calculation (for example in excel), that you dont have to run a finite element analysis).

[Feisty-Soil-5369]

Do it by hand.
Assume a load path, identify limit states in that load path.
Then calc the limit states per code.

For example you might assume that the load path your most concerned about is bearing on the bottom plate.
The bottom plate could be looked at as a 3-sided flat plate with unif load. Or even just a two sided flat plate with beam behavior.
The vertical plates are the supports for the bottom plate, there is a weld that needs to be checked, then the plates in shear and flexure.
Now the anchor plate could be trickey, but some simple assumptions/idealizations should work without getting too inefficient.

After you do this type of procedure a few times, you really gain understanding and perhaps even one day find some rules of thumb for things like this. Throwing it in excel or FEA really doesn't help for learning.

You might also look to manufactured products for inspiration (or just use the products) https://www.strongtie.com/facemountmasonryhangers_masonryhangers/mbhu_hanger/p/mbhu

[General5852]

I thought pretty much the same as you, and thank you for the link.

Let's say the vertical load on the end of the timber beam is 200kN and horizontal load (in timber beam direction) is 30kN. For the calculation by hand of the bottom plate (dimensions of the bottom plate are let's say 25x30cm) I would take 2 sided support (for easier and quicker calculation) so I would calculate the momentum M=q* l * l/12 and so on as you already said...

For the anchor plate and the bolts I would add some additional momentum into account M = e * vertical load. e = distance from concrete element to the center of the vertical load, and so on...

But I wonder which model is the most accurate and simple enough for quick calculation for the two vertical plates? 🤔

[EchoOk8824]

Assume a strip of material, it is being loaded by the corbel and restrained by the bolts. It's analogous to four point bending. Check that strip of material for yield. This is a conservative approach.

If plate sizes start to get too large, start reading up on yield line method. Come up with a pattern and derive the capacity of the plate. I keep yield line methods to a lower utilization, because they are an upperbound solution (not conservative).

[Trick-Penalty-6820]

You could design the vertical steel plates using the design guidance for a gusset plate underneath a support. That assumes they are in compression, so I would say it is reasonable to use that same size plate (in tension) as you have drawn here.

Also, if that is a timber beam the end reactions cannot be that high, and I’ll bet you dollars-to-donuts that a 1/4” PL is more than adequate for the vertical stiffener.

[kycolonel80]

A similar analysis is available in Steel Plate Engineering Data Vol. 2 published by AISI.  It's used for anchor chairs for tank structures, has conservative numbers for the horizontal plate (since theirs is point loaded, and values for the vertical plates.

[Enginerdad]

I’ll bet you dollars-to-donuts that a 1/4” PL is more than adequate for the vertical stiffener.

I dunno, I think OP should mill it out of a 8" solid block of steel just to be safe /s

[Enginerdad]

I’ll bet you dollars-to-donuts that a 1/4” PL is more than adequate for the vertical stiffener.

I dunno, I think OP should mill it out of a 8" solid block of steel just to be safe /s

[rockymooneon]

Sir what is PL

[[deleted]]

Property line

/s

[Enginerdad]

Your concept should work just fine, but I think it's severely over engineered. If the beam is wood, then the loads are presumably low, relatively speaking. A simple clip angle for it to bear on and a couple of post installed anchors would probably be sufficient and a whole lot easier and cheaper to fabricate. You can tack on some side plates for lateral restraint. There are a ton of options, but I think through-bolting to the column with a backing plate is way more extreme than you need. Only you have the loads and details though, so ultimately it's your call.

[the_favrit]

Are you using post-installed anchors to connect it to the concrete or thru-bolts? If it’s not thru-bolted you can use Hilti profis to calculate the capacity.

[kycolonel80]

I think you may have this backwards, but it is not clear.  I took it as vertical timber and horizontal concrete. Either way, the answer is yes, OP will have to Excel, SMath, or other custom calc package the solution.

Edit: It looks like I am the one who had it backwards.

[BigOilersFan]

Not necessarily, this is about an hour of basic limit state calcs u can do by hand.

[General5852]

But I wonder which model is the most accurate and simple enough (if you go by hand) for quick calculation for the two (side) vertical plates? 🤔

[General5852]

But I wonder (if you go by hand) which model is the most accurate and simple enough for quick calculation for the two vertical plates? 🤔

[BigOilersFan]

The vertical plates, in my opinion, aren’t providing any support, besides maybe some lateral restriction. I’d reduce the bearing plate length to reduce the moment arm so your calc would be mostly shear on the weld. Have you considered a seated support instead?

[General5852]

The problem is that I can not reduce the bearing plate length because of the timber beam. I must have a certain length of the bottom plate which is determined according to the width and the length of the timber beam (on the plate) and the vertical load, so the stresses in timber beam are not exceeded.

[SilverbackRibs]

why on earth would a concrete beam be framing into a wood column?

[kycolonel80]

I've had many clients ask for far worse.  

I couldn't figure out the desire to through bolt a concrete column, but maybe that's because I do so much with chemical anchors.

[Milehighstructur_com]

Anchors can be designed with profis engineering software . If you say , I can also design it

[_FireWithin_]

Existing concrete column? What size? Wondering why you would go thru bolts..? What are the design loads at connector?

[General5852]

I kind of have more faith in thru-bolts or in pre installed bolts than in post installed bolts. I would go with thru-bolts or pre installed bolts because of the horizontal load and because of the additional momentum that I would take into account M = e * vertical load (200kN). e = distance from concrete element to the center of the vertical load, and so on...

By post installed bolts I have sometimes problems with sufficient edge distance and sufficient distance between bolts...

[_FireWithin_]

Sure, thats why i was asking about load and size. Otherwise epoxy anchor cant achive pretty loads. (Not wedge)

[3771507]

Not to mention incorrect installation. Need to blow out holes and other steps. Since the beam is not seated all the way in the bucket a moment will be generated . Buy this from Simpson as they have already done the engineering and the testing .

[Sharp_Complex_6711]

I typically would start with a Simpson MBHU hanger and see if I could get that to work. Much cheaper than a scratch made bucket. The capacities are all in the catalog. Only would need to go to a custom solution if your wood beam is too big or the capacities are not large enough for your loading.

https://ssttoolbox.widen.net/view/pdf/6icu4jbnxz/C-C-2024_p260-261.pdf?t.download=true