Need a book? Engineering books recommendations...

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

Re: Brick shelf angles

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Ralph:

And a lot of those failures are more than likely caused by not paying
attention to movement issues with masonry.  Most masonry problems that I
have dealt with/evaluted were caused by poor detailing, lack of
appropriate movement joints, improperly sized movement joints, etc.  The
basic structural engineering portion of masonry (i.e. amount of rebar,
allowable stresses, etc) is relatively straight forward...the difficult
part of masonry comes with the "small" stuff associated with detailing it,
especially for shrinkage/expansion.  And while most problems arising from
poor detailing fall into more of a "nuisance" category (i.e. leaks,
cracks, windows jamming, etc), they can also lead to major structural type
problems (i.e. veneers failing of the buildings).

So "stretching things" is a relative term.  You can go pretty "far" with the
"basic" structural engineering portion, but that matters little if you
don't detail things properly, especially when dealing with movement
joints.

Regards,

Scott
Adrian, MI


On Wed, 17 Nov 2004 Rhkratzse(--nospam--at)aol.com wrote:

> I know practically nothing about brick veneer, however I do recall seeing a
> number of news articles in various construction industry publications over the
> past few years indicating that there's a fairly serious problem with veneer
> failures, brick among them.   Presumably these are older buildings.   Since we
> probably all hope that our projects will eventually become "old," I suggest not
> being too liberal in stretching things.
>
> Ralph
> Ralph Hueston Kratz
> Structural Engineer
> Rhkratzse(--nospam--at)aol.com
>
> 510-236-6668
> Fax 510-215-2430
>
> 724 McLaughlin Street
> Richmond CA 94805-1402 USA
>
> In a message dated 11/16/04 9:06:36 PM, smaxwell(--nospam--at)engin.umich.edu writes:
>
> > Kevin:
> >
> > While I cannot offer any thoughts on Canadian codes, I will comment on
> > what I recall from a US point of view.  I cannot recall any direct
> > provisions in the engineered masonry sections that place prescriptive
> > retrictions on vertical spacing of brick relief/shelf angles.  I have not
> > reviewed things too closely in a while, so there might be some changes in
> > newer codes.
> >
> > From past experience, the spacing is largely dictated by
> > architectural/aesthetic reasons in combination with the engineering
> > requirements.  The thing that typically gets in the way with going too far
> > is movement characteristics (i.e. expansion/shrinkage characteristics).
> > If memory serves me (it has been a while since my last masonry veneer
> > project), I have done stacked brick on the foundation for about 3 stories
> > then a relief/shelf angle that supported up to another 2 stories of brick
> > before the next relief/shelf angle.  The real limit is how big the
> > movement joint below the relief/shelf angle needs to be and how badly the
> > archtitect wants that joint to be obvious/not so obvious.  The practical
> > limit usually is about 2 to 3 stories of brick.  And the practical limit
> > for the amount of brick that you can design the angle to support is about
> > 2 stories max.
> >
> > But, otherwise, my experience is that the engineering principles along
> > with architectural/aesthetic reason are what you use to decide it...not a
> > presciptive code requirement.
> >
> > HTH,
> >
> > Scott
> > Adrian, MI
> >
> >
> > On Tue, 16 Nov 2004, Kevin Below wrote:
> >
> > > What is the maximum vertical spacing for brick veneer shelf angles ?
> > > The Canadian masonry code S304.1-94, Clause 16.9.4 for empirical design
> > > of brick veneers states 11 metres to the first shelf, then a maximum
> > > spacing of 3.6 metres.
> > >
> > > I would like to be able to use 2 story spacing above the 11 m if
> > > possible for a concrete-frame building, total of 5 stories of brick
> > > facing.  That would translate to a single shelf angle ( at level 4)
> > > instead of 2 (at levels 4 and 5).  And with the price of shelf angles -
> > > apparently 225 $ a metre, about 75 $ a foot, (does that sound right ? I
> > > am still not convinced, but that's what the construction manager says),
> > > it's worth doing the research.
> > >
> > > The Masonry Institute at HYPERLINK
> > > "http://www.masonryinstitute.com/veneer/section2.4.7to2.4.8a.html"http:/
> > > /www.masonryinstitute.com/veneer/section2.4.7to2.4.8a.html  says that
> > > the 3.6 metre (12') limit was intended for wood stud framing, I suppose
> > > to relieve the shrinkage problems of wood.  Concrete framing has some
> > > shrinkage problems too, but normally not as much as wood.
> > >
> > > Since the code requirement in Canada is for empirical design, are there
> > > any Canadian engineers out there with an opinion on whether this
> > > requirement is binding or not ?  If I do a rational analysis and show
> > > that the expected shrinkage over 2 stories can be taken up with a single
> > > shelf angle, I think that it would satisfy the code, since it would not
> > > be an empirical design, and so would not come under clause 16.
> > >
> > > I would ask my friendly building official, but we don't have them in
> > > Quebec.  So no-one is going to challenge my decision, but I would like
> > > to do the right thing anyway.  Some of professional ethics thing I
> > > suppose.
> > >
> > >
> > >
> > > Kevin Below, ing., Ph.D.
> > >
> > > GÉNÉCOR CIVIL INC.
> > >
> > > 290, rue Seigneuriale
> > >
> > > Beauport, (Québec) G1C 3P8
> > >
> > > Tél. : (418) 660-6969 poste 272
> > >
> > > Fax : (418) 660-6463
> > >
> > >
> > >
> > > ---
> > > Outgoing mail is certified Virus Free.
> > > Checked by AVG anti-virus system (http://www.grisoft.com).
> > > Version: 6.0.796 / Virus Database: 540 - Release Date: 2004-11-13
> > >
> > >
> >
> > ******* ****** ******* ******** ******* ******* ******* ***
> > *   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 
******* ****** ****** ****** ******* ****** ****** ********