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Help me to understand a bearing system of this barn

Help me to understand a bearing system of this barn

(OP)
I'm designing a barn and investor wants the same barn look/bearing system as Wolf System has.

For those who are not familiar with it:
All columns are steel columns, they are all pinned at support and they support primary timber beams. Outer steel columns are IPE 270 sections and inner columns are circular cross sections. Primary timber beams as glued – laminated timber section that are supported on steel columns. Secondary timber beams on top of primary beams (biaxial bending). Light roofing on top of secondary beams.

Bearing system : inner steel columns supports primary timber beams and are loaded with axial forces only (compression). They are pinned at supports (RC wall, foundation or slab).

What I do not understand is how is this construction laterally stable in transverse direction?

In Y (longitudinal) direction I see no problem since there are X bracings between outer columns (2 or more vertical fields between columns are braced). Bracing between two outer columns also continue into roof planes. Since columns are connected at the top with roof I can see how lateral force in longitudinal way is transfered to X bracing which made structure stable in this direction.

But how the hell is structure stable in X (transverse) direction? At first I thought that all outer steel columns are fixed at supports so they act as cantilevers. But I saw an anchoring detail and its clear they are also pinned at supports. So we have all columns pinned at the bottom. In order to achieve stability in X direction the connection between columns and primary timber beams has to be a moment connection!? Right? I dont see how is this possible tho…

Both outer sides of barn (walls) are made as timber trusses which are lateraly stable in this direction (X direction), so if there would be a diaphragm in a roof system that could mean that whole transverse lateral force can get transfered to outer walls of barns, but there are no such thing in a roof plane (no sheating - dont mind first photo bellow).

There is a video on youtube about buidling structure like this: https://www.youtube.com/watch?v=Z_pQc7UWOjk




















RE: Help me to understand a bearing system of this barn

pics on their website they show some cable or rod bracing. I think the last picture you can see in the first bay.

RE: Help me to understand a bearing system of this barn

It seems that someone is counting on some fixity in the wide flange base.

RE: Help me to understand a bearing system of this barn

Looking at the connection between the IPE column and the glu-lam beam, I would venture a guess they're also treating that as a moment resisting connection. long plates onto the flanges of the glu-lam would generate some fixity.

RE: Help me to understand a bearing system of this barn

I vote moment connections at the beam column joint. It can be done and looks as though it has been here. Maybe base fixity too, hard to tell. One way or another, transverse moment frames of some kind seems to be the order of the day.

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: Help me to understand a bearing system of this barn

The exterior columns have stiffeners which you would expect in a steel moment frame. So there must fabricated connections built into the glulam. Concealed or semi-concealed, they are there, but as to the details, not sure.

RE: Help me to understand a bearing system of this barn

There are fabricated steel connectors attached to the wood member. You can see them in the following 5 minute video starting at minute 1:40.

https://www.youtube.com/watch?v=VOKYnoivldk

I don't think it will be practical to use the same system. The setup costs would be enormous.

BA

RE: Help me to understand a bearing system of this barn

A proprietary system like this creates lots of problems for anyone trying to copy it. I wouldn't suggest that.

RE: Help me to understand a bearing system of this barn

(OP)
thats what i thought... Damn... im kinda screw.ed now, I dont know how to brace this thing in transverse direction. I can make outer steel columns fixed at support but Im wondering if this would work at all. Also it would mean huge spread footings.
perhaps I can replace outer steel columns with RC columns.

RE: Help me to understand a bearing system of this barn

Have you asked the company about the possibility of importing? I suppose it would depend on where you are located, and how important the look is to your investor client.

RE: Help me to understand a bearing system of this barn

Greznik91:
For all the guesswork here on E-Tips, why don’t you ask the manuf’er. of the bldg. how they handle the lateral loads and what the wind loads/speeds are? We don’t know what their gravity or lateral design loads are, but would like to know. In any case it looks like a very neat, clean structural system. Particularly if some of the bldgs. have been standing for 15-20 years, those barns are for some pretty expensive animals. That also appears to be a pretty well developed manufacturing plant and process too, all CNC cutting equipment, etc, I’ll bet.

I’ll vote for rigid gable frames, all columns pinned at the found. and the two middle pipe columns pinned at the GluLam too. There are moment connections at the top of the exterior columns and at the ridge btwn. the two GluLams. BA’s video shows about .375-.5" top and bot. flg. pls., maybe a bit heavier end pls., and a slightly lighter web pl. all cut and dapped into the GluLam beam ends. Essentially the same detail will work at the ridge and at the ext. columns. There are about 140-150 heavy timber rivets in each of the two t&b flg. pls, that’ll get you pretty large T&C forces for a moment couple. Then the ends are bolted up as if you were making up an end pl. moment connection in a stl. bm. All the stl. is galvanized, beautiful. Hokie may have the right idea about purchasing the bldg. and importing it. I suspect we couldn’t compete with their manufacturing system at first, but I have a GluLam supplier within a few miles of my house who could do those frames if I did the design. For years I did their structural analysis and design, their layout and geometry checking, and their hardware and connection design. Them was the days, a slide rule for the design and then trig. and log tables for the layout checking. I bought my first electric (plug-in) calculator, really only trig. functions as new added features, but many decimal places for that layout work.

RE: Help me to understand a bearing system of this barn

I bet the cost *is* the main issue here. Wolf *has* a subsidiary in grezniks country.
I doubt we could do it cheaper and better (as hokie and dhengr wrote) as a one-off thing. Maybe the investor would be open if you could do it cheaper in full-steel. Wooden beams look really nice, but i bet cows dont care much, and investors like money in the pocket:)

RE: Help me to understand a bearing system of this barn

What is the magnitude of forces in your case? I do not think that is very difficult to replicate those connections with a modern timber framer that is setup with the CNC equipment being used. In Europe, that is fairly common equipment in some regions. That said, if cost is an issue that would be heading down the wrong path. None of what you have pictured is cost effective. You need a clear understanding how much your client is prepared to spend. We have worked with barn owners and we have never had the luxury to deal with one that is willing to spend a lot more to make the building unique.

Here is one European connection company. They list they do post and beam engineering, maybe they have something or could help. We have used concealed connections like they have pictured. It was interesting to work with tight tolerances.
http://www.knapp-verbinder.com/wp-content/uploads/...

If this all seems feasible for your client I would talk with a glulam supplier early into the design. They are the most motivated to solve this problem because they have the most to make on the project. A connection company does not have the margins on a project like this to invest a lot of time. We work with one glulam manufacturer occasionally and they have a brilliant connection designer that is very good at solving the problem of connecting wood parts.

RE: Help me to understand a bearing system of this barn

I see and design a lot of barns, and tax dollars pay for a lot of ag buildings in Canada (sorry farmers, but you are subsidized way more than the average Joe), but this looks a zillion miles beyond what any farmer I've ever run across would spend to house his family, never mind his cattle. I include my cousin in that group, who just spent a couple million insurance dollars to replace a complete dairy operation after a huge and disastrous fire. His new barns and related facilities are beautiful, but not like this; it is simply beyond my field of experience for an agricultural use. There are lots of ways to enclose this space more cheaply, so if this is the look your client wants, find the phone number for Wolf & give it to him.

RE: Help me to understand a bearing system of this barn

Don't miss the possibility that there are no excess (nor sufficient) resistance. Mistakes have been made before, and the Code-limiting/Code-breaking loads just have not appeared yet. So the building sits there.

If each joint was bolted up tight and firmly torqued, each joint does become able to resist a limited sideways load. Even the baseplates drawn will have some limited sideways resistance. Add up a bunch of small resistances, combine that with no extreme wind loads (yet), and the building stands.

To improve resistance, why not add cables tensioned in a cross at every frame bay? Not just the roof as in the last photo, but in every open bay. If the lower attachment point of each cross were not at floor level, but 1.0 to 1.5 meters above grade level, there still be room to walk through easily.

RE: Help me to understand a bearing system of this barn

(OP)
Thanks for replies guys! I agree with what you have suggested.
Original Wolf system was 'too expensive' so we left that option behind. But its kinda logical taht replication of this can be even more costly.
As far as I know you cant guaranteee/provide a moment connection between steel/wood so they must have some lab tests that approve such connections?
Ill propose to replace primary timber beams with steel beams so I can make moment connections with columns.

RE: Help me to understand a bearing system of this barn

Ofcourse you can create moment connection between steel column and timber beam. Much easier than timber-timber. It also possible to take stiffness of the connection into account. Just need to dig deeper in timber engineering books. Maybe I can help, I'm from same area and specialise in timber structures.

RE: Help me to understand a bearing system of this barn

Why is the rod/cable bracing not sufficient?

RE: Help me to understand a bearing system of this barn

Where are these structures located? Probably not a Seismic Design right?

RE: Help me to understand a bearing system of this barn

the rod and cable bracing is sufficient in the one direction, but not in the other. Based on the length of the building I doubt the roof diaphragm can span end wall to end wall. Therefore some form of intermediate support is required.

You can most certainly provide a moment connection between a wood beam and a steel column. As Molibden indicated it is much easier than a wood-wood moment connection.

RE: Help me to understand a bearing system of this barn

Looks like shear walls in the other directions for most of them.

RE: Help me to understand a bearing system of this barn

(OP)
molibden, Id really appreciate if you can post some links to engineering books/articles and especially examples od calculations on steel-wood moment connections. In university we havent done a single one! Everytime there was timber involved connections were pinned.

RE: Help me to understand a bearing system of this barn

Knee braces can be used to achieve moment connections between steel columns and wood beams. Joints may be pinned, but the connection between column and beam is restrained.

BA

RE: Help me to understand a bearing system of this barn

Looks like a pole structure to me with metal columns. Base fixed, but not the top.

Mike McCann, PE, SE (WA)


RE: Help me to understand a bearing system of this barn

(OP)
I guarantee you that base of columns are not fixed but pinned.

RE: Help me to understand a bearing system of this barn

I would tend to agree. It appears the baseplate it at the top of stem wall (which also looks fairly narrow). I can't expect much fixity from that configuration. I'm 99% sure they've created moment connections with the steel plates extending on either flange of the wood beam. Wouldn't be surprised if there was also a steel knife plate to create the shear connection. It's actually rather elegant.

If the owner wants a cheaper type structure with a similar look, BA makes a great point about knee braces. They're cheap, easy and reliable.

RE: Help me to understand a bearing system of this barn

You can see moment connection in your first photo you posted. There are steel plates welded/bolted to columns (similar in the ridge) top and bottom of timber beam. Probably they you self tapping screws to connect steel plates and wood. You can drill holes in plates at 45 degrees (or use special washers) and use tension resistance of the screws rather shear. Wurth, Rothoblaas, SFS... have a lot of these details in their catalogs for products.
Another way is to have steel plates vertical, cut in the middle of timber beam and use bolts in double shear connection. Also there are glued in rods, Wurth ZD-platte and many more...
Be careful with timber shrinkage perpendicular to grain - minimise restraint so wood can shrink/swell.

RE: Help me to understand a bearing system of this barn

(OP)
Loads wont be that small so for someone who hasnt got any experience with that type of connections I think its smart to choose another path - steel beam instead of glu-lam beam. Im really not comfortable with designing something im not familiar with and structure is 20 m x 50 m... Im wondering do Eurocodes even cover this type of connection? Ill have to check...

RE: Help me to understand a bearing system of this barn

With Eurocodes you can design screws, bolts, steel plates etc. You will not find "timber moment connections" in there.

RE: Help me to understand a bearing system of this barn

(OP)
TNX, Ive just found out that. Well, I wont be a hero for the money I earn in company I work for... I ll go with steel beams and steel moment connections. Any replication of Wolf system would not be cheap and I wont sleep well either. So 2 wrongs is a no go...

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