Identify this wall bracing type?

I am looking for help identifying this type of wall bracing in a historic barn in Iowa. One pic is the roof structure layout directly above the interior wall bracing pic.
I appreciate any help

https://www.dropbox.com/sh/g3skm47tpfisktz/05Y36XnOVQ

Hello,

Perhaps Jan will see this or Rudy, but If I had to guess this is a horizontal bracing truss (note the iron rods) that is meant to stiffen the valley and gable wall connection. I would would note also, that this is "transitional balloon framing" from the more vernacular and classic timber framing systems that you can find in older barns of Iowa. This barn presents as circa date 1890 to 1930, or contemporary replica of the same time period.

Hope that helps,

jay

I thought it was a type of 'balloon framing'. The barn is 1902, open raftered with two hand hewn 'balloon rafters' running east/west above central vertical supports.

I was explaining to the current owner that the bracing was apparently to provide stability and strength to the side walls where they became load bearing so the walls wouldn't belly out, I just wasn't certain of the term for the bracing.
Thanks!

You "nailed it" with your explanation IMO. That "hand hewn" rafters would be the indicator, (plus the date) that this is "transitional" barn architecture from the iconic timber frames of the vernacular.

Beautiful structure, thanks for sharing and asking the quesiton.

Interesting. That is essentially a horizontal queen post truss.

Jim

Jim, can you give me any more information on the horizontal queen post truss?

Hi Jim,

I was curious as well? The load dynamic in Go-figure's photo places the to metal roads in a tension load, while in most vertical queen post truss systems (perhaps not all) they are in compressive load. I believe this assembly would be called a "hip truss" assembly.

Regards,

jay

i'll take a stab at it - if you wind load the wall, the wall wants to bend in, pushing the bottom chord into to building. this would want to pop the top chords out, away from the wall. the rods act in tension, holding the top chords tight to the horizontal 'tie' that is 4-5 feet off the wall, stiffening the wall.

a typical qp truss or kp truss loads the bottom chord in tension (assuming no load transfer from a loft floor, etc), or in bending a bit in a qp, where the qp's might load the bottom chord. in this instance the wall is being loaded, and the bottom chord being pushed up into the truss, which wants to pop those top chords open.




larger image:
https://lh6.googleusercontent.com/-rVbl5...10.21.31+AM.png

Mike, I have a wholly different take away from the photos, more are needed. I think this was a plain building renovated to fancy. The interior rafters with sheathing in place is the tip off, in some manner, the interior rafters have a role in supporting the roof system without any ordinary bracing at the rafter feet. So if indeed, the interior rafters impart steady static thrust load to the plate, the queen post truss configuration makes sense and will hold together, as it must have. That style of truss rod construction was championed by
Trautwine in his engineering handbook. Trautwine wanted to rename the queen post truss to a queen rod truss, basically stating that since the term post implies compressive loading, rod is the more suitable term since the qp is in tension.

As far as I can see, (more photos) this building seems to lack balloon frame and timber frame detail, so I feel that the building technique is platform framing without the succession of floor levels. What I can see gives the feel of a fancy carriage house not a barn.

agree on the tension in a qp truss, in most uses. wasn't thinking about those interior rafters. was thinking about wind loading.

this building, which was done by new energy works (before my time there) uses a horizontal truss to take the load on all that glass. you can barely see it in there.





link to larger photo.
http://lh6.googleusercontent.com/-_YCOYQ...ide244+copy.jpg

look at second truss in, bottom chord area, you'll see steel tension rod coming back away from the window, acting as a horizontal truss.

its pretty crazy, what history does to buildings. would be interesting to uncover some story about this.

Mike, I've seen steel rod re-enforcement on the underside of beams on old commercial buildings in a similar fashion to the N.E.W. frame. I think the gable wall bracing could be improved because walls can be sucked out or in under high wind conditions. If the king post to ridge braces were lengthened to past the point of bypassing then I think a more secure wall could be obtained.

A drawback to the rod re-enforcement is that under heavy load the narrow bar can overload the psi capacity of the wood grain.

Hi,

Metal in tension and wood in compression can be combined to good effect to make a working structure that takes full advantage of the properties of these quite disparit materials.



Ken Hume

Thanks to all for all the great information! It has given me much to research. I will try to visit back with this owner and get some better pictures! The barn was revitalized in the Historic Barns of Iowa program, hence the sheeting that can be seen. The rafters and trusses are original, just some re-roofing.

CAnn