Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Plywood shear walls with 3x sills...

[Subject Prev][Subject Next][Thread Prev][Thread Next]
I've been following this thread lately.  Seems as though there was some
discussion earlier in the year.  I'm not sure if the following applies to the
sills, but as far as 3x members at vertical panel joints, I ran across the
following in APA report #157.  Page 21 second paragraph, "If multiple studs are
used in lieu of solid one piece wood framing at panel edges, the studs must be
fastened together to transfer the shear forces that the shear wall is designed
for.  This may call for closely spaced face nailing of studs with 10d or 16d
common nails, or perhaps bolts or lag screws.  When multiple studs are used,
sheathing fastening should be apportioned between these members".  Seems to me
that they are saying multiple studs may be used with the fastening criteria.
Another option I have heard is using a 2x vertical member situated with the wide
face against the sheathing with a typical 2x stud either side.  Seems this would
work for the "3x nominal" criteria at least for 8d nails since the penetration
required is 1.5".  Any thoughts out there?

Joseph Grill, P.E.





Dave Adams wrote:

> Hello again,
>
> I have a few questions regarding U.B.C. Table 23-II-I-1, footnote no. 3
> (fourth printing):
>
> 1.  The requirement is that in seismic zones 3 & 4 where "allowable shear
> values" exceed 350plf, 3x sill plates and 3x framing members where panel
> edges meet are required. Suppose I had a shear wall with 19/32" C-D plywood
> on both sides of the wall with 10d nails at 6"o.c. The individual "tabulated
> allowable shear value" is 340plf, however with two layers, the "total
> allowable shear value" would be twice as high. Since the "tabulated" value
> of the individual panel used is less than 350plf, would the 3x member
> requirements still apply?  [By the way, I think this is a silly question
> since, practically speaking, It seems that the intent is for the allowable
> shear value of the "total" wall pier (i.e. regardless of whether one or two
> layers of plywood is used), not just the tabulated value. I believe this
> came in response to Northridge.]
>
> 2.  How does this requirement relate to "upper-level" shear walls? They do
> not have "foundation plates" nor "anchor bolts".
>
> 3.  I've had some contractors whine (no...really?) about this, saying that
> they either cannot get 3x pressure-treated members or they are very
> expensive. Some building officials also are not enforcing this
> (no...really?). Anyone run across this?
>
> Thanks for your responses (in advance).
>
> Dave K. Adams, S.E.
> Lane Engineers, Inc.
> Tulare, CA
>