Wood shear wall FTAO
Wood shear wall FTAO
(OP)
General talking point: Anyone know of limitations to the aspect ratio of the side segments on a wood shear wall when the Force Transfer Around Openings method is used? Published or otherwise? I know the limits for the perforated and segmented method are documented are are reasoned to limit wall flexibility. The FTAO method is not so codified though.
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MAP





RE: Wood shear wall FTAO
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MAP
RE: Wood shear wall FTAO
"2305.3.8.1 Force transfer around openings.
Where shear walls with openings are designed for force transfer around the openings, the limitations of Table 2305.3.4 shall apply to the overall shear wall, including openings, and to each wall pier at the side of an opening. Design for force transfer shall be based on a rational analysis. Detailing of boundary elements around the opening shall be provided in accordance with the provisions of this section[see Figure 2305.3.5(b)]."
Interestingly this is not in the the IBC-2012 or as best I can tell NDS-2012 or SPDWS-08.
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MAP
RE: Wood shear wall FTAO
RE: Wood shear wall FTAO
I don't know why I couldn't find that before
I see 4.3.4.2 applies the ratio table to the piers and defines them.
Anyone know a rational basis for the 2' limit?
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MAP
RE: Wood shear wall FTAO
For these narrow situations I've always wondered how a built up plywood box beam (cantilevered up from the floor) with hold downs would work. The problem might be web buckling and am not sure there is a calc for that but it would be an interesting approach.
These shear walls keep getting narrower and narrower....
EIT
www.HowToEngineer.com
RE: Wood shear wall FTAO
So ranting done. 2'-0" limit seems somewhat arbitrary while being mostly reasonable. Anybody familiar with the source of this?
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MAP
RE: Wood shear wall FTAO
RE: Wood shear wall FTAO
I just want to engineer the nuts off a wall because I can (it is a sick pleasure but a darn good one
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MAP
RE: Wood shear wall FTAO
Take a look at M410 report from the APA. Lots of testing in there.
http://www.apawood.org/level_c.cfm?content=pub_sea...=
Personally I'd like to learn more about their "advanced" modeling techniques, which they say are not "reasonable" for the typical practicing engineer... I'll be the judge of that :)
Woodworks has a presentation regarding the M410 report which is OK I suppose. I thought the 24" came from the M410 report but it does not appear so. They actual test a wall with an 18" segment (wall 12). Does the commentary in the provisions for wind and seismic say anything about it?
EIT
www.HowToEngineer.com
RE: Wood shear wall FTAO
Nothing in the commentary or even a reference tag specifically. There is this document in the reference list which looks like it might be close to what I am looking for but not really helpful ultimately because it seems to support not using 24" as a limit: www.apawood.org/pdfs/TSD/T-Reports/T2005-08.pdf
Hmmm.
My ultimate reason is to know if I should put a lot of emphasis on 24" being safe or if it was just some back room compromise and it is a nice round number and increment of blah blah blah. What if I have 23" because the R.O. of the window is just so. and the architect says "dammit you are screwing up the symmetry in this room and EVERYBODY can tell its wrong, it is just an inch. what's the big deal". to which my response would be: [dumb sheepish looks]. I love that feeling.
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MAP
RE: Wood shear wall FTAO
If you haven't found an answer to your question about 24" minimum wall segments you might want to try the AWC Help Desk at
(202) 463-4713 or the apawood Product Support Help Desk at (253) 620-7400.