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Re: Strap hold down detailing

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could be, I was doing the EE work, and the structural engineer says the ends of
the garage had these things for the shear wall.  I was concerned as need a 14"
elec. box to go in there.

John Turner, EE

Ted Ryan wrote:

> Are you referring to Hardy Frames?  Never heard of Harvey Walls...
>
> Ted Ryan
>
> ----- Original Message -----
> From: "John Turner" <jdkjt(--nospam--at)pacbell.net>
> To: <seaint(--nospam--at)seaint.org>
> Sent: Saturday, January 01, 2005 5:56 AM
> Subject: Re: Strap hold down detailing
>
> > When you say wall frames, have you any info on "Harvey Walls"?  They are
> > proposed on the 2'5" end walls for townhouses at the double garage doors!
> >
> > John Turner, PE
> >
> > "Bill Allen, S.E." wrote:
> >
> > > Chuck -
> > >
> > > FWIW, my question was general in nature and was relative to all coil
> straps
> > > up to and including CMST12s.
> > >
> > > Regarding the 2nd question, I try to provide a hold down for all
> calculated
> > > uplift forces >0. Sometimes I go to wall frames to eliminate uplift
> forces.
> > >
> > > Regards,
> > >
> > > T. William (Bill) Allen, S.E. (CA #2607)
> > > ALLEN DESIGNS
> > > Consulting Structural Engineers
> > > http://www.AllenDesigns.com
> > > V (949) 248-8588         .       F (949) 209-2509
> > >
> > > -----Original Message-----
> > > From: chuck utzman [mailto:chuckuc(--nospam--at)pacbell.net]
> > > Sent: Tuesday, December 28, 2004 11:41 PM
> > > To: seaint(--nospam--at)seaint.org
> > > Subject: Re: Strap hold down detailing
> > >
> > > Bill's post implied a "lightly" loaded shearwall, say 1/2" CDX w/ 10d@6"
> > > loaded at about 100 to maybe 140 plf. On an 8' post that's 800 to 1100
> > > #. These days I'm using more & more engineered joists (to eliminate the
> > > shrinkage problem) & on an upper floor CS16 x 4' seem about right with
> > > nails at every other hole. Since the shear is in the plywood, the strap
> > > nails suck it out before it gets into the post. The nailing above the
> > > strap are the only ones lifting the post (which is why Simpson's
> > > Strongwall tiedowns are set kind of high on their corner posts IIRC).
> > >
> > > That does bring up another question. Where are you guys setting your
> > > cut-off value for tiedowns? After talking to Ed Diekmann & some other
> > > S.E.'s with a lot of wood-frame design experience, I decided on 800#. I
> > > just had a big dispute with a young, outside plan checker who thought
> > > the number should be 0. (My calculated net uplift was 300# & this
> > > particular location was very difficult to access, so I said no.)
> > >
> > > I don't see the straps as any more susceptible to shrinkage than PHD's.
> > > Around here we're framing with green D.F. which dries very slowly (until
> > > the the building is closed-in & the occupants turn on the heat). With
> > > green, sawn 2x12 joists the only way I can see to address shrinkage is
> > > with a tensioning coupler like Simpson's TUD. At $50 each that seems a
> > > little pricey but YMMV
> > >
> > > Chuck Utzman,P.E.
> > >
> > > Ed Tornberg wrote:
> > >
> > > > This is a subjective response - sorry, no numbers.
> > > >
> > > > "How much is enough?" is fairly straightforward with respect to
> > > > gravity loads.
> > > >
> > > > "How much is enough?" is complex, sometimes vague, esoteric, and
> > > > sometimes mind-numbing with respect to lateral design.
> > > >
> > > > For the majority of wood-frame buildings, because of the many
> > > > unaccounted and redundant, lateral force resisting mechanisms, as well
> > > > as the multiple factors of safety, I'm more and more inclined to not
> > > > subject the inner workings of holdown detailing to thesis-level
> > > > scrutiny. Especially for wind-governed elements.
> > > >
> > > > But for a structure that doesn't have the redundancies, say a large
> > > > commerical shell building, or a "high liability risk" structure, like
> > > > multilevel multifamily, I'd "do more".
> > > >
> > > > I agree with the other posts approving of straps over sheathing,
> > > > especially if it's a lightly loaded shearwall.
> > > >
> > > > Ed Tornberg
> > > >
> > > > Tornberg Consulting, LLC
> > > >
> > > > 503-551-4165
> > > >
> > > > -----Original Message-----
> > > > *From:* Bill Allen, S.E. [mailto:T.W.Allen(--nospam--at)cox.net]
> > > > *Sent:* Thursday, December 23, 2004 10:34 AM
> > > > *To:* seaint(--nospam--at)seaint.org
> > > > *Subject:* Strap hold down detailing
> > > >
> > > > Now that I'm just relaxing (just waiting for USC to show OU exactly
> > > > what an "average" offense is like), I thought I would throw out a
> > > > question to find out how others do things.
> > > >
> > > > Currently, I detail straps to be installed over the plywood (oops,
> > > > Wood Structural Panel) sheathing. Otherwise, it would be difficult to
> > > > install the SW edge nailing. Simpson has load tested this condition
> > > > and they believe it is O.K. to install it like this. I know there may
> > > > be some who don't like this installation, but for the purposes of this
> > > > topic, let's assume it's O.K.
> > > >
> > > > For CS straps, which are 1-1/4" wide, a single 2X stud may be adequate
> > > > for anchorage. Similarly, for CMST straps which are 3" wide, double 2X
> > > > studs would be a mimumum and may be adequate for anchorage (both for
> > > > tension and compression). Let's assume that they are for the purposes
> > > > of this topic. With this scenario, how do you address the stud which
> > > > has the shear wall edge nailing as well as the strap nails? I've heard
> > > > where some folks omit the edge nailing at the strap. For short straps,
> > > > this doesn't seem to be much of a problem. A CS16 has an end length of
> > > > 11" with 10d nails and 14" with 8d nails. However, with a CMST12, the
> > > > strap is more than half the height of the shear wall. I'm having
> > > > trouble reconciling forces with a FBD (load transfers from the SW into
> > > > the end post back through the SW into the strap).
> > > >
> > > > Of course, one could make the end post wider to allow the edge nailing
> > > > to run past the strap. For a CS, that would require a double stud. For
> > > > a CMST, that would require 3-2Xs. I don't have so much of a problem
> > > > with the larger strap (of course, all of the multiple studs would have
> > > > to be face nailed to transfer the load from the edge nailing to the
> > > > hold down strap), but it seems to me that this **might** be "overkill"
> > > > for a lightly loaded CS strap. After all, CS20, CS18 and CS16 straps
> > > > have capacities of 1,030 lbs, 1,370 lbs and 1,705 lbs respectively.
> > > >
> > > > Opinions and comments are welcome.
> > > >
> > > > Regards,
> > > >
> > > > T. William (Bill) Allen, S.E. (CA #2607)
> > > >
> > > > *_ALLEN DESIGNS_*
> > > >
> > > > Consulting Structural Engineers
> > > >
> > > > http://www.AllenDesigns.com <http://www.allendesigns.com/>
> > > >
> > > > V (949) 248-8588
> > > >
> > > >
> > > >
> > > > .
> > > >
> > > >
> > > >
> > > > F (949) 209-2509
> > > >
> > >
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