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





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
RE: Help me to understand a bearing system of this barn
RE: Help me to understand a bearing system of this barn
RE: Help me to understand a bearing system of this barn
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
RE: Help me to understand a bearing system of this barn
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
RE: Help me to understand a bearing system of this barn
perhaps I can replace outer steel columns with RC columns.
RE: Help me to understand a bearing system of this barn
RE: Help me to understand a bearing system of this barn
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 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
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
RE: Help me to understand a bearing system of this barn
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
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
RE: Help me to understand a bearing system of this barn
RE: Help me to understand a bearing system of this barn
RE: Help me to understand a bearing system of this barn
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
RE: Help me to understand a bearing system of this barn
RE: Help me to understand a bearing system of this barn
BA
RE: Help me to understand a bearing system of this barn
Mike McCann, PE, SE (WA)
RE: Help me to understand a bearing system of this barn
RE: Help me to understand a bearing system of this barn
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
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
RE: Help me to understand a bearing system of this barn
RE: Help me to understand a bearing system of this barn