Need a book? Engineering books recommendations...

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

Re: Strap hold down detailing

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Chuck:

To some degree you are likely right...they more than likely don't test
each configuration of every strap.  I say this based upon experience with
ICC/ICBO acceptance criteria for other products.  Based upon my
experience, there will be some testing done.  You can then use calculated
values for interpolated situations (within reason).  Typically, however,
you cannot use exterpolated values...you at a minimum have to test the
"boundaries" and then can calculated in between those "end points".  It
could, however, be different for the acceptance criteria for such
manufacturered wood connectors.  FWIW, if you really want to know, you
should be able to go onto www.icc-es.org and find the acceptance criteria
that Simpson uses in the evaluation process.  Heck, you could ask someone
at Simpson which AC it is and then go look at it.  They might even say
which AC in their ICC/ICBO evaluation reports.

Regards,

Scott
Adrian, MI


On Thu, 23 Dec 2004, chuck utzman wrote:

> I go over the plywood & consider the strap nails sufficient to serve as
> the local plywood EN (it's also then possible to see what they did &
> verify strap/nails).
>
>  I've also not been comfortable with such close nail spacing on the
> stud, so I bump the length up & tell them to nail every other hole.  I'd
> be very uncomfortable about stud splitting with both sets of nails in a
> 2x.  I'll better you a nickel that Simpson's values are calculated, not
> tested, for a lot of these straps.
> Chuck Utzman, P.E.
> Bill Allen, S.E. wrote:
>
> >
> >
> >
> >
> >
> >
> > 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
> >
> >
> >
> >
> >
>

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: http://www.seaint.org 
******* ****** ****** ****** ******* ****** ****** ********