Foundation to Post Connections Part Two

[Jim_Rogers]

I recently went to a barn raising in VT. At this "hand" raising the posts were connected to the concrete foundation using a "hinge plate" this was something totaly new to me, and a lot of the other timber framers. And I'm not sure who designed it or if it was fabricated there at the school. But it worked great and seem quite easy to install.
Here are some shots of this "Hinge Plate"
Jim







I did not see them installed but it appears that the top half of the plate was attached to the post using a screw called a panel screw. These screws are used to connect structual insulated panels (sips) to frames. The base plate seems to have some type of tar paper under it and the bolts are secured to the concrete. These bolts had to be cut off using a grinder to allow enough clearance for the hinge to close.
Once the hinge was closed by the raising of the frame the whole hinge was repainted by a student of the school.
Some of these hinges were not connected together until the "bent" was being raised, this meant that the raising had to be stopped mid way up to allow the "hinge pin" to be slipped in, once the "hinge" halves were aligned. But that only took a few seconds and it went very smoothly.
I hope these photos can help some of you, to fab your own plates.
Jim

[DanG]

Those hinge plates look interesting, Jim. Do they lock in place after raising?  I will consider making some of them if I ever do any timber framing.
What are some of the more traditional methods of attaching the bents to the foundation? :P

[Greg]

Those hinge plates look interesting, Jim. Do they lock in place after raising?  I will consider making some of them if I ever do any timber framing.
What are some of the more traditional methods of attaching the bents to the foundation? :P

The (Sobon shed) frame I'm working on has 8x8 sills all around. The sills traditionally set on a flat rock foundation, but I'm going to use either piers or simple 8x8x16" concrete blocks.

The bents have small tenons on their bottoms and drop into 2" stub mortises on the sill. If anyone likes I will try to scan/post a detail of a typical sill/post connection.

This attaching posts to concrete stuff is a quite a new-fangled concept ;-)

Greg

[DanG]

Thanks, Greg. Your explanation is pretty clear, but pics are always welcome here. ;D
Florida has some pretty stringent strength requirements, especially on anchoring to the foundation. If I build a timber frame house, I'll have to go with the strongest connection I can get. I'm thinking of a block foundation on a poured footer with a 4x8 sill plate bolted to that.

Fla requires plywood sheathing all around, but I don't know if that would apply to a timber frame with an engineer's signature. We'll just have to see, when the time comes.

[Greg]

Thanks, Greg. Your explanation is pretty clear, but pics are always welcome here. ;D
Florida has some pretty stringent strength requirements, especially on anchoring to the foundation. If I build a timber frame house, I'll have to go with the strongest connection I can get. I'm thinking of a block foundation on a poured footer with a 4x8 sill plate bolted to that.

Fla requires plywood sheathing all around, but I don't know if that would apply to a timber frame with an engineer's signature. We'll just have to see, when the time comes.

Supposedly the weight of the large bent assemblies is supposed to hold them down on the sills by gravity only, but boy that doesn't "feel" very secure to me either!

I'm sure hurricane and earthquake areas have the need for alot more "beef" to these connections. Another option I've heard of is simpson straps going as far around as the entire perimeter of the building!

By sticking to building/selling smaller size structures, I'm hoping to avoid some of the red tape and expense of meeting codes and signed drawings in my state. At some point, a house turns into a outbuilding, but I'm not sure when ;-)

Hopefully a ~ 12 x16' and smaller backyard shed will fly me under the beaurocratic radar screen...

Still have got some homework to do to understand the relaity of Ohio, KY, and Indiana building codes.

Cheers,
Greg

[OneWithWood]

Gregg,

You've got some work to do in Indiana.  The building codes are county specific.  :P

[Jim_Rogers]

DanG;
There are many ways new and old to attach to foundations. But Greg was right in the olden days the timbers just sat on the stones, no straps or anchors that I've heard of.
But as mentioned you are in a high wind area and maybe you should consult your building inspector and find out what he will require and then design your fastening system based on this info.
If you have an engineer's stamp on your drawings, what does your engineer suggest for fastening it down to the foundation?
A continuous supported sill, will be good, but the post locations should be beefed up to support the point where the load will be applied. You might have to pour some concrete into the blocks and add some rebar to make the post locations stronger.
If this is the case you can add a sill bolt shaped like a "j" into the poured concrete and then bore a hole threw the sill, recess the nut below the surface of the sill (if necessary) and then the sills will be anchored to the foundation.
here is a shot of the plans for the barn in VT showing a "j" shaped bolt being used in the piers and the foundation wall to attach the sill boards to:


"J" shaped bolts at red arrows.

I'm not sure if you can see it, but the posts are over the long "j" shaped bolts/rebar and the other sills boards are bolted down with the shorter "j" shaped bolts.
Jim
PS. I thought I heard them talking to a welder, maybe the man who created these hinge plates about welding the two halves together, in place. If so, I don't understand why they had the student paint them first, unless they were just trying to find something for him to do. But if I can find out I'll let you know about the welding in place.
Also, did you see my other posts about foundation connections? I have lots of other types of these connectors in the CAD programs library.

[Jim_Rogers]

The designer of the hinge plate asked me to post a drawing of his design.



Also he told about this design on another timber framing forum, here is his posting:

Some clarification on the Vershire Mountain School hinged post bases. The panel screws from upper plate into post end grain are only locators. The real base-to-post connection is an inch and a half vertical pipe (1.9-in. o.d.) welded to the upper plate and inserted into a two inch diameter hole in post end grain. The pipe is, of course, invisible after installation.

In addition to horizontal restraint, this pipe can also provide hold-down capacity via a horizontal bolt/pin through posts and pipe. We did not bother with this in Vershire since structural analysis indicated that barn dead load exceeded predicted uplift by a safe margin (discounting any help from the vertical siding nailed to mudsills anchor bolted to the foundation).

Upper and lower hinge plates were welded together after the raising (the reason for the originally unpainted parts of the fixtures). Lower plates were bolted to the foundation with four three-eighth inch Hilti HVA adhesive anchors, two of which could easily handle side load or zero gravity uplift.

For future discussion there is a much more elegant prototype hinged post base on the drawing board waiting for an appropriate project. Ed Levin

Thanks to Ed for his help with the drawing.

Now we all can understand the proper use of this type of post to foundation connection.

Please also read the post: "Foundation to Frame Connections, A Word of Caution"