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RE: ACI 530-02/ASCE 5-02/TMS 402-02 Experts

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Barry:

There is no specific commentary for section 6.2.2.3.1.5.  What I posted
early is basically it (there is more commentary for section 6.2.2.3 but I
just posted what appeared to be directed at section 6.2.2.3.1.5).  If it
will help, here is the rest of the commentary for section 6.2.2.3 (the
paragraph I posted last time was the last paragraph...here are the
others):

"6.2.2.3 Vertical support of anchored masonry veneer - These requirements
are based upon current industry practice and current model building codes.
Support does not need to occur at the floor level; it can occur at a
window head or other convenient location.

The full provisions for preservation-treated wood foundations are found in
the National Forest Products Association Technical Report 7 (ref 6.9).

There are no restrictions on the height limit of veneer backed by masonry
or concrete, nor are there any requirements that veneer weight be carried
by intermediate supports.  The designer should consider the effects of
differential movement on the anchors and connection of the veneer to other
building components.

Support of anchored veneer on wood..."

(I won't type the last paragraph again)

I believe that there are two different "things" that I seen the provision.
One is addressing the situation of possible differential settlement due to
some masonry sitting on a stiffer material such as the foundation while
other might be sitting on wood.  The provision in question requires that
you put a joint between these two situations to "isolate" them.  This will
prevent nature from putting a joint there for you (i.e. a vertical crack
that would likely form due to different movement due to the different
supporting material).

The second thing in the height (and weight) restriction.  As I read it,
you can place no more that 12 ft of masonry that weighs less than 40 psf
on wood supports.  The provisions does not say that this 12 ft must be
from ground level, so it would seem that you could have 12 ft (or less) of
masonry veneer supported by a wood header that is above a window or
supported by a second floor framing system.  So, at best, it is just a 12
ft limit of masonry supported by a wood system or member.  At worst, it is
supposed to be a limit of 12 ft from the ground, but is not clearly
articulated as that.

I will point out that the IRC also permits masonry to be supported by wood
construction, but under VERY limited situations.  And the 1997 UBC
basically bars such construction except under VERY limited exceptions.

HTH,

Scott
Adrian, MI


On Tue, 31 Aug 2004, Barry H. Welliver wrote:

> Thanks Scott.
>
> Is there a specific commentary on section 6.2.2.3.1.5?
>
> I guess I'm confused by the wording in the cited section 6.2.2.3. If the
> presumption is that differential settlement is addressed with a "vertical
> movement joint", then "where are the bodies?"
>
> Also, you mention 12 feet as the maximum single story height considered
> reasonable for fire safety. Does this imply 12 ft off the ground or 12 ft of
> masonry height (at levels above 12 ft.)
>
> I know Harold Sprague has suggested the arguments for this provision
> (6.2.2.3.1.5) were born of considerations for a falling height of 12 or
> greater, but I'm trying to be engineer here and do what is right for my
> client without tripping over the code.
>
> To help those who may be interested (or tired) in why I'm nit-picking, I
> have a two story existing concrete home with a wood frame roof with
> projecting eaves. The architect is proposing to add a limestone cornice
> (veneer) wrapping the roof edge. This would be 20 or so feet above grade and
> I've envisioned a double microlam fascia supported by microlam cantilever
> beams. The members are significantly stronger than required by analysis and
> the veneer attachments would be screwed to this backing. If fire is a
> primary consideration, I could use triple members and perhaps achieve a
> heavy timber rating.
>
> Any help in justifying or trashing this solution would be appreciated.
>
> Barry H. Welliver
> barrywelliver2(--nospam--at)earthlink.net
>
>
> -----Original Message-----
> From: Scott Maxwell [mailto:smaxwell(--nospam--at)engin.umich.edu]
> Sent: Tuesday, August 31, 2004 9:49 AM
> To: seaint(--nospam--at)seaint.org
> Subject: RE: ACI 530-02/ASCE 5-02/TMS 402-02 Experts
>
> Barry:
>
> Here is what the commentary of the 2002 MSJC says for section 6.2.2.3:
>
> "Support of anchored veneer on wood is permitted in previous model
> building codes.  The vertical movement joint between the veneer on
> different supports reduces the possibility of cracking due to differential
> settlement.  The height limit of 12 ft (3.7 m) was considered to be
> maximum single story height and is considered to a reasonable fire safety
> risk."
>
> It would appear that some of the concern of supporting masonry on wood is
> due to the combustible nature of the wood (but that may just be me reading
> "between the lines").
>
> HTH,
>
> Scott
> Adrian, MI
>
> On Fri, 27 Aug 2004, Scott Maxwell wrote:
>
> > --------------------------------------------------------------------------
> > Your following message has been delivered to the list
> >   seaint(--nospam--at)seaint.org at 17:59:21 on 27 Aug 2004.
> > --------------------------------------------------------------------------
> >
> >
> > Barry:
> >
> > Harold has already provided you with some good comments.  I will add to
> > his comments that historically it was not permitted to support any masonry
> > on wood construction with some very limited exceptions.  A good example is
> > in the 1997 UBC (Chapter 21, I believe but don't remember for sure as I
> > don't have it right in front of me).  I believe (going from memory here)
> > that older versions of the MSJC (ACI 530, etc) had similar
> > restrictions/limitations, but that changed in the 2002 MSJC.  As I am
> > currently out of town, I don't have the 2002 MSJC in front of me at the
> > moment, but I will endevour to remember to look at it when I get home and
> > see if they have any relevant commentary for that section.
> >
> > Regards,
> >
> > Scott
> > Adrian, MI
> >
> >
> > On Fri, 27 Aug 2004, Barry H. Welliver wrote:
> >
> > > I'm just up from my nap.
> > >
> > > I appreciate your insight on this matter Harold. I was afraid there was
> > > "thinking" along this line. By your comments, I presume there is little
> > > explanation of this in the new commentary and applaud your intention to
> > > follow through at your code development meeting.
> > >
> > > My own experience with code change proposals has reinforced the need for
> > > good commentaries to help the users grasp a changed or new provision. I
> also
> > > realize how difficult writing those commentaries can be. Perhaps if the
> > > proponents where required to provide verbiage for the associated
> commentary
> > > (to be published at the same time) the essence of the arguments would
> also
> > > have to be agreed to.
> > >
> > > I try to keep copies of the code change proposals specifically because
> they
> > > contain information about the logic of the proposition. I'm familiar
> with
> > > this in the IBC process. Is there a similar source for ACI/ASCE/TMS
> > > approvals?
> > >
> > > Thanks again for being a well-spring of information for this listserv.
> > >
> > > Barry H. Welliver
> > > barrywelliver2(--nospam--at)earthlink.net
> > >
> > >
> > > -----Original Message-----
> > > From: Harold Sprague [mailto:spraguehope(--nospam--at)hotmail.com]
> > > Sent: Friday, August 27, 2004 12:05 PM
> > > To: seaint(--nospam--at)seaint.org
> > > Subject: RE: ACI 530-02/ASCE 5-02/TMS 402-02 Experts
> > >
> > > Barry,
> > > I happened to be awake during the time that this was discussed in some
> of my
> > >
> > > seismic code development participation.
> > >
> > > This was a reaction to a lobby by the residential building community.
> Prior
> > >
> > > to this, it was prohibited to support ANY masonry from wood.  The
> resulting
> > > code was a compromise.  But masonry should not be supported by wood if
> the
> > > masonry is 12 ft from grade.  The argument presented at the time had
> nothing
> > >
> > > to do with the weight supported by wood.  The argument presented was for
> > > prohibition of a falling hazard.   I am sure that I could design wood to
> > > support much more than what the code infers.  We have been remiss in
> > > Commentary development.  I will make it a point to discuss this at our
> next
> > > code development meeting... right after my nap.
> > >
> > > Regards,
> > > Harold Sprague
> > >
> > >
> > >
> > >
> > >
> > > >From: "Barry H. Welliver" <barrywelliver2(--nospam--at)earthlink.net>
> > > >Reply-To: <seaint(--nospam--at)seaint.org>
> > > >To: "Seaint Listserv" <seaint(--nospam--at)seaint.org>
> > > >Subject: ACI 530-02/ASCE 5-02/TMS 402-02 Experts
> > > >Date: Fri, 27 Aug 2004 09:54:06 -0600
> > > >
> > > >First of all I have to say keeping up with "code changes" is adding
> grey
> > > >hair on a daily basis now.
> > > >
> > > >
> > > >
> > > >An exception in section 6.2.2.3.1.5 allows support of masonry veneer on
> > > >wood
> > > >framing provided that the masonry has an installed weight of 40 psf or
> less
> > > >and height of no more than 12 ft.
> > > >
> > > >
> > > >
> > > >  My understanding of the 12 feet is a veneer weighing less that 40 psf
> up
> > > >to
> > > >that height (i.e. 40 psf x 12 ft.) is the maximum load allowed for wood
> > > >support. It has been suggested that this means masonry weighing 40 psf
> > > >cannot be installed higher than 12 above the ground. If this (second
> > > >suggestion) is correct, I'd like to know.
> > > >
> > > >
> > > >
> > > >Secondly, if this provision is intended to limit the weight of masonry
> > > >being
> > > >supported (and that's a big if), then would a single stone (such as a
> > > >lintel, jamb or sill stone) which has a density exceeding 40 psf but
> weighs
> > > >significantly less than 40 psf x 12 feet, be "acceptable" as a rational
> > > >interpretation (and hence be supportable on wood framing).
> > > >
> > > >
> > > >
> > > >Thanks for any help on understanding this "new" provision. As you might
> > > >tell
> > > >from my "inexperience" with ACI 530-02, I've yet to get this resource
> and
> > > >associated commentary.
> > > >
> > > >
> > > >
> > > >Barry H. Welliver
> > > >
> > > >barrywelliver2(--nospam--at)earthlink.net
> > > >
> > > >
> > > >
> > >
> > > _________________________________________________________________
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