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RE: Relative Stiffness of Wood Shearwalls

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Dennis:

Yes, Hardy Frames will be designed and manufacturer with "compliance" with
ICC ES PFC-5342, which is Hardy's ES evaluation report.  That report,
however, is "created" by way of following the requirements (for testing
and other supporting documentation) of AC130 (AC stands for acceptance
criteria).  AC130 is the acceptance criteria used for getting an
evaluation report of propriety or prefabbed shearwalls.  It contains the
testing and other supporting information requirement that Hardy must do in
order for ICC ES to approve and issue an evaluation report.

And AC130 specifically requires that they do testing for three conditions:
direct on concrete foundations (what the reports shows in the tables for
"FOUNDATIONS"), on first floor sill plates (the "WOOD SILL PLATE" tables),
and raised upper level floors (the "RAISED FLOOR" tables).  What I don't
really know is how many different wall configurations (i.e. aspect ratio
and wall length) of each base condition they need to test.

And to clarify, I was referring to AC04, not ACI 04, when talking about
the acceptance criteria for SIPs.  ICC ES AC04 is the acceptance criteria
that structural insulated panels (SIPs) must follow in order to obtain an
ICC ES evaluation report.

HTH,

Scott
Adrian, MI


On Thu, 27 May 2004, Dennis Wish wrote:

> Scott,
> Compliance is with ICC ES PFC5342 and the frames are designed to comply
> within division 04- Metals, section 05400 - Cold Formed Metal Framing.
> Design on concrete states the following under the ES report section 2.6.6:
> "Normal-weight concrete must have a minimum 2,500 psi compressive strength
> at 28 days. The concrete materials must comply with Section 1903 of the 1997
> UBC or Chapter 3 of ACI 318-99 (under the 2000 IBC and the 2000 IRC)."
>
> There is no specific reference to ACI 04 that I could find in the ICC
> report.
>
> Hardy's (as well as ShearMax and others) are empirically tested, but the
> information I received from both Hardy and Shearmax is that you may use a
> straight line interpolation to calculate the deflection and capacity on
> non-standard frames that lie between standard frame heights. I was told that
> a straight line interpolation (by Hardy Frame) was considered to be
> conservative on their 12, 18 and 24" panels only. We did not discuss Frames.
> ShearMax will (for a reasonable fee) test any panel height and width that is
> non-standard for those wanting more exact information. However, when I posed
> the problem I had, I was recommended to use a straight line interpolation to
> obtain conservative values.
>
> Dennis
>
>
> Dennis S. Wish, PE
>
>
> California Professional Engineer
>
> Structural Engineering Consultant
>
> dennis.wish(--nospam--at)verizon.net
>
> http://www.structuralist.net
>
>
>
>
> -----Original Message-----
> From: Scott Maxwell [mailto:smaxwell(--nospam--at)engin.umich.edu]
> Sent: Wednesday, May 26, 2004 10:00 PM
> To: seaint(--nospam--at)seaint.org
> Subject: RE: Relative Stiffness of Wood Shearwalls
>
> Keith/Dennis:
>
> While I am certainly no expert on ICC ES AC 130 (which is the acceptance
> criteria that I believe Hardy and other propiertary shearwall manufacturer
> must use to gain their ICC ES evaluation report), I do believe that it
> does require the manufacturer to test most (if not all) different
> configurations of their prefabbed/propiertary shearwall.  This can include
> different support conditions (i.e. on concrete foundation, on wood framed
> first floor, on wood framed upper floor, etc) as well panel sizes/aspect
> ratios.  And I believe that it means that the values that they have in
> their report come from testing (although there might be an analysis
> option...but from my experience with ICC ES on AC 04 [for SIPs] they are
> not too terrible fond of the analysis options at times).
>
> Regards,
>
> Scott
> Adrian, MI
>
>
> On Wed, 26 May 2004, Keith De Lapp wrote:
>
> > I too spoke to Hardy just yesterday before sending my previous email.  The
> > point I was trying to make with you was that you said, something to the
> > effect...I don't care what the numbers say, I don't combine different
> > systems in the same line...  Or something like that, I believe the intent
> of
> > your thought is clear.  You mentioned that intuition and experience tell
> you
> > not to.  Which is fine.  I believe clarification may be in order though.
> We
> > each have "our way" (ie some rational) to add either redundancy or
> ductility
> > which we believe improves LFRS performance.
> >
> > I thought the comment you made was liken to forget what P over A plus M
> over
> > S tell me, I'm gonna do something different.  Now not exactly, but sort
> of.
> > Considering the world stage this forum is being viewed on, I thought the
> > topic warranted further consideration.  To me relative stiffness is
> > foundational and I'm sure you agree.  And, I don't take "the numbers" as
> > gospel.
> >
> > But your remarks sounded a bit, "prescriptive" to put it in building code
> > terms.  Which surprised be coming from you.  I referenced the Hardy Frame
> > because if testing is only used to verify the allowable shear and drift
> > based upon calculations, then I don't see a difference with enveloping the
> > performance of a plywood wall and a Hardy Frame based on a relative
> > stiffness calculation.  There probably isn't a one of us who hasn't used
> > steel to reinforce a tilt-up panel opening retrofit for out-of-plane loads
> > using relative stiffness.  The elements don't know how the load gets
> there,
> > they just do what their geometric/material properties demand they do.
> >
> > Would you recommend a Hardy Frame "Panel" and "Frame" be used in the same
> > line?  Or how about a Hardy Frame installed on concrete and another
> > installed on a wood sill plate and another installed on wood framing?
> Each
> > of the above two cases will vary in relative stiffness (all other things
> > being equal), now swap in a plywood shearwall and you have the exact same
> > problem.  You have to pay attention to their relative stiffnesses to see
> how
> > the load will be shared throughout the LFRS system.
> >
> > The preaching is not meant to be belittling in any way, it's just a style
> > thing.
> >
> > Keith De Lapp, P.E.
> > KDL ENGINEERING
> >   -----Original Message-----
> >   From: Dennis Wish [mailto:dennis.wish(--nospam--at)verizon.net]
> >   Sent: Wednesday, May 26, 2004 9:09 AM
> >   To: seaint(--nospam--at)seaint.org
> >   Subject: RE: Relative Stiffness of Wood Shearwalls
> >
> >
> >   Keith,
> >
> >   I spoke with Hardy the other day and this is not correct. Their values
> are
> > based on testing and their current ICC reports indicate that the drift
> > calculations can be interpolated in a straight line interpolation which is
> > considered conservative to their test data. Hardy (Mitek) has been
> listening
> > to this thread and I would recommend that they respond to your comments.
> > They asked if it was appropriate for them to participate and I felt it was
> > as long as they were not attempting to sell product. I think they are in a
> > better position to respond to you than I am, but I do know that they
> > recommended an interpolation of in plane drift based on height changes in
> > each frame or panel. Also, as I mentioned, when different panels/frames
> are
> > used in the same line of shear, the drift/stiffness should be calculated
> > based on relative rigidity.
> >
> >   Shearmax also uses an interpolation for non-standard frame heights. I
> have
> > not spoken to Simpson or TJ, so others may respond to this.
> >
>
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