cantilever wood diaphragm
cantilever wood diaphragm
(OP)
Does anyone know of a GOOD reference for cantilever wood diaphragm design examples? Also, for a 3-sided building, i.e. 3 sides with shear walls and one "open" or window wall?
I am looking at a tiny 12'x18', one story cabin that has slab on grade under the back third (12'x6.5'), and the rest cantilevered over post and pier. To make it even more interesting, the outermost 12' wide wall is all window with 4 posts.
I've got a few ideas for design, but I think I'm stretching the code a bit. Steel moment frame over cant diaphragm??? Seems too much, but this building is so tiny.
Thanks,
I am looking at a tiny 12'x18', one story cabin that has slab on grade under the back third (12'x6.5'), and the rest cantilevered over post and pier. To make it even more interesting, the outermost 12' wide wall is all window with 4 posts.
I've got a few ideas for design, but I think I'm stretching the code a bit. Steel moment frame over cant diaphragm??? Seems too much, but this building is so tiny.
Thanks,





RE: cantilever wood diaphragm
RE: cantilever wood diaphragm
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: cantilever wood diaphragm
Attached is a 6 page .pdf of the cabin.
Thanks again gentlemen.
RE: cantilever wood diaphragm
We may also design for a 747 impact on the side, just for fun.
Seriously, I'm thinking of a square steel frame surrounding the windows. The bottom of which is a rim beam in the floor cavity. Then carry shear back to the foundation via cantilevered floor diaphragm. The loads will be fairly small due to the bldg size, but keeping it stiff will be the tough part. Also, piers under the frame will get larger than they show to resist HD forces.
If they'll buy it, I might go towards cantilevered columns in the front 2 corners, pole barn style. MUCH simpler, but the footings will be huge, and not I'm crazy about embedding posts in concrete for longevity/maintenance reasons.
RE: cantilever wood diaphragm
Just a thought
RE: cantilever wood diaphragm
RE: cantilever wood diaphragm
Try Design of Wood Structures ASD/LFRD, sixth edition by Donald Breyer, et al. You could also try the Engineered Wood Association (www.apawood.org). They have a lot of information available on line and it is free.
The book has some examples of a three sided diaphragm. Generally one has to determine if the diaphragm is rigid or flexible relative to the shearwalls.If the center of the lateral force does not coincide with the center of rigidity, the diaphragm will have the ability to rotate. As a result of the rotation the lateral forces will be redistributed between the shearwalls.
I hope that this helps.
RE: cantilever wood diaphragm
RE: cantilever wood diaphragm
RE: cantilever wood diaphragm
i got it to work with 4 wood "shear posts" tied into a short plywood shear wall that extends below the floor. I'll also detail the roof diaphragm to help carry load back to the side and rear shear walls as if it was 3-sided to make sure it stays stiff around the windows, but not having to prove all the 3-sided building calcs.