Need a book? Engineering books recommendations...

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

Re: Norbord Windstorm OSB panels

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Neil:

What is interesting to me is if they are using the NAHBRC report as their
basis for eliminating the need for hardware, then I find their conclusions
puzzling as that report clearly indicates that the shear wall test
assemblies were tested with a holddown (both shown in the pictures of the
shear wall assemblies and in Table 3 on page 6 of the report and in
general terms in Table 4 on page 7).  I don't know how one can jump to the
conclusion that holddowns are not required when the report on their
testing clears shows that a holddown was used in the testing.

In terms of general uplift resistance, the report does clearly indicate
that the failure mode as tested was in cross grain bending of the bottom
plate.  The summary states that in order to "suppress" the cross grain
failure mechanism plate washers must be installed at the sill anchor
bolts.  They did test this approach in specimen T4 and the result was that
the failure mode was no longer in cross grain bending of the bottom sill
plate.

So, to me the conclusions that one could draw from the test report is that
you can potentially resist uplift loads through the sill anchor bolts in
terms of overall uplift if plate washers are used.  One cannot conclude,
however, that end wall holddowns can be eliminated for shearwalls.

Regards,

Scott
Adrian, MI


On Wed, 15 Mar 2006, Neil Moore wrote:

> We've been reading (and commenting) on a OSB shearwall system for
> high winds that's being touted to eliminate hold-downs on the
> Eng-Tips website.  Has any of the list used these walls?  They
> apparently are using only anchor bolts at the sill plate, with the
> bolts resisting both sliding forces and uplift forces and have
> referenced this report:
>
> http://www.nahbrc.org/Docs/NewHomeNav/LaboratoryCertificationServices/4722_NORBORD1.pdf
>
> Also review their reasoning:  http://www.windstormosb.com/ws-method-high.html
>
> I can not find a ICBO report that provides data that an engineer can
> use to design their panels.   The laboratory report is utilizing
> cross-grain bending in the sill plate and referencing the Forest
> Products Wood Handbook for the tension values of at cross grain bending.
>
> The particular discussion can be found
> at:  http://eng-tips.com/viewthread.cfm?qid=149335&page=1
>
> Any comments?   Do you know of any building departments that will
> accept these type of shearwalls?
>
> Neil Moore, SE, SECB
> neil moore and associates
> consulting structural engineers
> shingle springs, california
>
>
>
> ******* ****** ******* ******** ******* ******* ******* ***
> *   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
> ******* ****** ****** ****** ******* ****** ****** ********
>

******* ****** ******* ******** ******* ******* ******* ***
*   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 
******* ****** ****** ****** ******* ****** ****** ********