Unique Multiple King-Post bent in barn frame.

[Rooster]

Hey Guys,

I found this photo of a barn located in Indiana.  The frame is 36ft x 50ft, and one of the interior bents creates a free-span hay loft system, using a multiple king-post truss.  I've only seen these in covered bridge frames, or frames with suspension rods holding up the lower cord...but never well above the sill and further up the bent like this one.

I just thought I would share before unique frames like these are lost to the passage of time.

Rooster



 

[Jim_Rogers]

Thanks for sharing...

[Jay C. White Cloud]

Hey Rooster,

That is beyond awesome!    Do you know who owns that?  or if they would ever consider selling it?  That can't be lost, if it can be avoided at all.  Can you imagine that inside a meeting room or house with a glass wall behind it, with just some highlights of stained glass, maybe a wing of a Church. 

Thanks for posting it!! 8)

[routestep]

From what I can see, I don't think that is a kingpost truss. At least not in the traditional sense. It looks like there are light rafters where the upper chords should be and they should go down to the lower chord. The kingpost tie into the lower chord is questionable.

It is unique though. Looks like it works.

[Jay C. White Cloud]

Hello Routestep,

You will have to expand your observation for me more, I see a truss in all since of the word.  Unless the King Post's only have stub tenons on them, which I doubt, they are forming a truss, as does the rest of the joinery in the upper and lower cord, as well as the oblique bracing-both mortised and lapped.

Regards,  Jay

[Bru]

Got more photos?

[routestep]

Another picture might help out here. Near the end where the wall post is.

The two Upper Chords looked like rafters to me. Maybe the Truss is those upper pieces?

Is this some type of a suspended lower lower chord? The kingpost is greatly extended to that long cross tie.

I don't know what the terminology would be.

[Rooster]

I'm working on getting more photos...then we'll see what's up!!!

Thanks,

Rooster

[Jay C. White Cloud]

Hi Rooster,

That would be great!  I sure wouldn't want to see this go under a salvager's saw.  It should be saved or repurposed as some other structure and kept whole if at all possible.

Hey Routestep,

The quick, (horrible-I did it free hand in under five minutes, please forgive) sketch may help.  I wish I knew how to make pictures bigger on the forum, but can't figure out if that's possible. I labeled the members as they are in most barn trusses I've worked on.  The King is not a post in this case but a "king strut,"  and the two outer posts in the truss are "queens."  Upper and lower horizontal beam are the "cords," of the truss, and the rest I think you can make out.  There is distortion in the picture, so I'm guessing at the layout and roof pitch, but I'm pretty sure it is a symmetrical not asymmetrical truss assembly.

Regards,  jay

[Bru]

Jay:  Your drawing sure was helpful to this newbie, in understanding the posts in this thread. Thanks.

[D L Bahler]

I see a bridge truss here. Not a roof truss like we are used to, where the top cords follow the roof slope or some such, but a truss where the cords are all horizontal.

From what I can tell of the picture, the reason behind this may well be to allow a very large open span on the bottom floor without any posts to interfere. What we have here is a bridge truss distributing the loads from the loft floor and even the roof out to the walls with no intermediate support. We can see behind that the gable wall is framed in a more traditional manner.

This may be a one of a kind barn, designed b a bridge builder or some carpenter who had a sound understanding of structural dynamics and was not tied down to following a set method of building. Where abouts in Indiana is this barn, I wouldn't mind a look at it if it aint too far!

[Jay C. White Cloud]

I've been dust'n off notes folks.  This is a nifty barn, close to rare but we have seen a few and more are coming on line, but not as nice as this one seems to be.  I sure don't want to see this one scraped.

Regards,  jay

[Rooster]

I'm leaning towards a bridge builder who also built barns, or at least a barn framer that learned from working on bridges.

The first frame that I cut was a covered bridge...and I used a multiple king-post truss system.

I recently was kicking some ideas around with one of my clients and came up with this for a free span "purlin system" for a new barn to be used as a "half court" type basketball gym.

It's fun to trouble shoot and use old technology and design to solve today's problems.

Rooster



  

[Satamax]

Rooster, if i say Ritter or Cullman, does that ring a bell?

[giant splinter]

In the first photo this frame appears to have a Pratt Truss out on the periphery and the transverse truss is very much a bridge type design in my opinion. I will have to agree with Rooster and D L Bahler on the Bridge truss thought, and I am looking for a midspan post under the mezzanine for some reason. <scratching head> this will be a good post for a structural engineer to have a look at.

[routestep]

Rooster

I really misinterpret the picture. Your drawing clears it up for me as to what the bent looks like. I never worked on a bridge, seen a few drawings, so I'll defer to those of you with that experience. This is a neat frame.

How deep into the lower chord do those post tenons go, all the way through?

The chord doesn't look that deep for spaning 36 feet!

[Jay C. White Cloud]

Hello Folks,

This topic of "engineering" and "strong enough," is coming up on several post threads.  I think what is important to remember for historical buildings, architecture over seas, and maybe your own work in some cases, is that the standards that we are "culturalized," in today are much different than you see over seas or in historical buildings.  I notice that outside North America, most domestic architecture is built in similar fashions to what you would find 500 or more years ago here in the U.S. or Canada. They follow empirical knowledge, tradition, and sit tested parameters, while most today follow a statistical amalgamation of numbers from charts that we then plug into formulas.

Our charts are based on studies with "mean averages," and other statistical compilations.  The engineering is linear in nature, that is why we often apply different formula to the loaded member, that way we can perhaps gather a more third dimension view of the components and it's potential loads.  Now factor in some of our "code standards," like 240/360 degree deflection of floors, and you can clearly see, just with these simple criteria, why we have such a divergence from today's work and our Elders.

A truss-of this design- over 11 meters (36') is more than strong enough to hold it's potential loads, (obviously it's still standing and working,) but in most likely would not meet modern criteria for deflection.  Much of Engineering, as well as code, have multiple levels of safety margin factored into it statistically and through it's applied formulas.

To answer the question about tenon length, I would only be speculating because I can't tell from the photo.  I can tell you that many go through, some had wedged tenons underneath.  Of the pass through and wedge type, many get cut off around the 1950 and 1970, and nails driven in, please down ask me why...it drives me crazy, because when I restore these frames, I have to try and put everything back.

I hoped that help some.

Regards,  jay

[D L Bahler]

This idea of historic structures being overengineered has come up a few times.
I have to disagree with this assessment.

Yes, these buildings are built to be able to handle more loading then they will ever encounter.

But structural and live loading is not the only consideration. These buildings are also engineered for mass. That is, the structures are made massive to afford stability etc. Also, they are over engineered so that the building 100, 200 300 or even further on down the road will still be able, with heavily degraded materials and even failed joints at times, to withstand that structural loads. They are engineered in anticipation of the future, not built to merely meet the needs of the present.
This shows the difference in modern thought compared to that of the past. We look at engineering in terms of what does the building need to function right now. So by our standards, these are 'over engineered'
I submit that any wooden building constructed to meet the engineering needs of the present only will encounter sever structural problems 50 years down the road, thus prving the point that it was actually 'under engineered' because it did not take these future problems into account.

[Jay C. White Cloud]

Hi D L Bahler,

In most cases, old structures are assessed as being "under" engineered not "over."  That is why I wrote what I did on post #17 of this thread.  We often have to prove that the old barn or house that has been standing or over two hundred years with a slate roof on it, is strong enough to become someones home.  I'm often trying to educated "new," engineers to the realities of this craft and where there charts and graphs come from.  Most of it is statistical not empirical to the specific job.  Posts, for example, are often over sized, as is common in folk architecture in general, but beam are considered undersized.  It is a rather confusing amalgamation.

[Rooster]

Hey Guys....look, a timber-framed bridge truss inside a barn!!!   ;D

Here are some more photos of some of the joints.  The lower tenons on the lower cord are through tenons and have 3- 1.25" trunnels at the two lowercord and king-posts.



  

  

  

  

  

  

   

  

  

 

[timberwrestler]

I disagree with the premise that there's a bridge truss in the barn.  There is a truss in the barn, but it's a truss that's not specifically associated with bridges.  If it was a Burr arch truss, then there certainly would be a bridge builder involved.  But if it's anything like what Jay drew, then that sort of truss could be found in a public building like a church, or town meeting hall.  The only other bridge-like characteristic that i can think of is camber in the chords, which would be pretty interesting if the barn showed.  Nonetheless, it's a very cool and interesting barn. 

I'm also with Jay, in that older structures rarely meet modern code requirements.  That's not to say that they were shoddily built (although some certainly were), but that the safety factors present in the load calculations and the required live loads of today's engineering makes it pretty unlikely for historic buildings to meet modern code.

[Rooster]

http://www.fhwa.dot.gov/publications/research/infrastructure/structures/04098/04.cfm

This link shows many bridge truss designs including both the MTP and the Burr truss.  This site helped me design the bridge that I build back in 2000.

I need to take a few measurements, and even a string-line to check for camber on this "truss-bent"...and I'm not sure how soon I can get over there.

All I know is that it is very impressive, and I can't stop looking at and studying how it was framed.

Thanks,

Rooster