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Re: Masonry Column, Ties Required?

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Thanks Scott,

I don't think they are needed either, I have considered trying my luck at it making it through the checker and field inpector. I guess one one more code argument with these guys will just be another drop in the bucket.



WILL


From:  Scott Maxwell <smaxwell(--nospam--at)engin.umich.edu>
Reply-To:  <seaint(--nospam--at)seaint.org>
To:  seaint(--nospam--at)seaint.org
Subject:  Re: Masonry Column, Ties Required?
Date:  Fri, 16 Sep 2005 08:44:54 -0400 (EDT)
>You are right on point in my opinion, but then so is Will in his response
>to this message.  While you are technically correct in terms of how
>members are typically described from a structural point of view, Will is
>also correct in that the MSJC's (ACI 530) definition does not talk about
>things like flexure vs. axial load, etc but only defines a column in terms
>of its relative cross-section dimensions and length.  So, Will is 100%
>correct (in my opinion) that by the MSJC's definition, he is dealing with
>a column.  As a result, his "concern" that a code official will thus
>require the ties is a valid question/concern.
>
>Will:
>
>The commentary might help a little.  First, it does kind of help with the
>arguement of a column is an axial load element...but then it also says
>that columns can have flexure too (which is true...but many times
>structural engineers then may call it a "beam-column").  Unfortunately,
>while I agree that what you have is really primarily what I would call a
>beam (i.e. something overwhelming governed by flexural/shear loads), the
>commentary is still not specific enough to even say that the INTENT is
>that the column provisions in the MSJC may not apply.
>
>The second are is that section 2.1.6.5 of the commentary does talk about
>WHY ties are required.  The first reason is just as mention in ASQuilala's
>post...to prevent buckling of the vertical bars under axial compression.
>So, at first blush, this would potentially provide you with an arguement
>as to why ties are not required.  But, then the second reason given is to
>provide diagonal tension resistance when loaded in shear.  And, thus, you
>are back to "square one" in that this requirement would "reinforce" (pun
>intended) the thought that you must provide ties.
>
>The options that I would explore that could "eliminate" the tie
>requirements are:
>
>1) Design the "grouted" core as a reinforced concrete vertical
>cantilevered beam and just have the brick be a veneer.  This would first
>require a close look at your X-section dimensions (you would want a "gap"
>between brick and the concrete so that the connection between the two
>would minimize composite behaviour...and whether or not something around
>8" will work per ACI 318).  You could then design per ACI 318 (assuming
>there is nothing in ACI 318 that would prevent it...i.e. such as minimum
>dimensions...but I don't recall any such limitations).  If so, then it is
>possible that the shear is small enough that stirrups/ties would not be
>needed for shear resistance.
>
>2) Argue that "building code" requirements are not required for a "fence
>post".  I believe that we had such a discussion in the past on the list.
>I tried looking in the archives some, but could not locate it (sorry, only
>willing to look so long).  I don't recall exactly how the discussion
>went/ended up, but I do recall discussing a similar issue (i.e. must fence
>posts be required to meet building code structural requirements).
>
>Now, my final "suggestion" is why not do what you think is appropriate
>(i.e. if you think ties are not needed, then don't provide them).  If you
>don't think ties are needed, but the plan checker disagrees, then it is
>not much effort to "add" them in (after all, I would have to believe that
>the odds of you getting NO plan check comments [from what I have
>seen/heard relative to what typically happens with plan checks...at least
>on the West Coast] is pretty nill, so it is not like you "gain" anything
>by avoiding this potential comment).  This is assuming that your only
>concern is that you will get a plan check comment and that you are
>completely fine with the idea that ties are NOT really required.  If you
>are not SURE if you believe ties are not required, then that is a whole
>other matter.
>
>Regards,
>
>Scott
>Adrian, MI
>
>
>On Fri, 16 Sep 2005 ASQENGG2(--nospam--at)aol.com wrote:
>
> >
> > The word column and beam are terms to describe structural members.  Beams
> > generally are subjected to flexure while columns are those that carry  large
> > axial loads.  Since the member you describe does not carry large  axial loads but
> > instead is subjected to bending moment then it should be  treated as a beam.
> > The main function of ties is to prevent buckling of the  reinforcement.  Since
> > there is no chance that the reinforcement will buckle  in the absence of
> > large axial loads, then there is no need for  ties.  Structural members should not
> > be designed for their name  or call outs but on the nature of forces or loads
> > they are being subjected  to.
> >
> > ASQuilala Jr., P.E.
> >
> >
> > In a message dated 09/15/05 1:56:55 P.M. Pacific Standard Time,
> > gtg740p(--nospam--at)hotmail.com writes:
> >
> >
> > I have an equipment yard with 16" brick columns (4" brick  around perimeter
> > with an 8" solid grouted  core). They are about 9ft tall  and at 10ft spacing
> > with a nearly solid metal fencing between them. The only  axial load the
> > pilasters are taking is their own self weight.
> >
> > Are ties required?  It appears ACI 530 requires ties for  "columns" no matter
> > if they are taking vertical load or not. The "columns"  seem to be acting
> > more like cantilevered beams to me. The wind shear is only  about 1400 lbs at the
> > base of the columns.
> >
> >
> > Will
> >
> >
> >
> >
> >
> >
>
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