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RE: CMU Column Ties (horizontal)

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Scott,
Two issues:
1. The columns are non-structural
2. As I noted in another post, the engineer who brought this to my
attention indicated that at least vertical OR horizontal steel was
required and if vertical was required; it was his opinion that the
horizontal ties were not required. Inasmuch as this is not brick, I
can't see that the horizontal ties would be necessary in fully grouted
cells spaced at 8" o.c. typically. 

Scott, considering this is your field of expertise, I accept your
interpretation, but consider that this is a non-structural fence post
and let me know if this changes your opinion or the opinion of the other
engineer that believe that either vertical OR horizontal reinforcing
needed to be provided. I am at a loss as I don't see the necessity of it
due to the fact that it is in block and not brick and that all cells are
fully grouted.

Thanks
Dennis

-----Original Message-----
From: Scott Maxwell [mailto:smaxwell(--nospam--at)engin.umich.edu] 
Sent: Sunday, November 16, 2003 3:16 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: CMU Column Ties (horizontal)

Dennis:

I don't have my UBC with me, but I do have the 2002 MSJC (masonry code).
Section 1.13.6.5 requires the use of ties (at least #3) in columns at no
more than 8" OC for Seismic Design Catergories D, E, and F.  This would
equate roughly to zone 3 or 4 in the UBC.  Presumably, the UBC has a
simillar provision.

In addition, section 2.1.6.5a requires that lateral ties enclose
longituduinal reinforcement.  The ties must be at least #2 bars.
Section
2.1.6.5b gives the spacing requirements.  Thus, it would seem to me that
if you don't have vertical reinforcement then you don't need ties.

HTH,

Scott
Ypsilanti, MI


On Sat, 15 Nov 2003, Dennis Wish wrote:

> I have a client who created 24" square columns 6'-0" tall that are
> spaced at approximately 10'-0" on center and surround a pool. Wrought
> Iron fencing will infill the area between the columns which seem to be
> installed for looks only. A three foot wide gate will be placed
between
> two of the columns, but the gate will be supported upon its own
> stanchion.
>
> The client used 4x4x16" CMU in creating the columns and installed #4
> vertical rebar at each corner and at 8-inches around the grid. He did
> not install any horizontal steel and the city inspector (this was done
> without engineering) will not allow the cells to be grouted until an
> engineer verifies that the horizontal steel is not needed.
>
> I'm not sure I understand what purpose the horizontal steel has in
this
> case where the blocks are overlapped and the vertical steel locks them
> together. Also, this is not part of a structure as it is nothing more
> than a fence post. However, if there is a requirement for horizontal
> steel I need to know what section of the code I might be violating. I
> went through the Masonry Handbook (Amhrein's (?)) but was not able to
> find a reference for this. Also, this is not brick but concrete
masonry
> units and it is not tied to any structure but is self-standing.
>
>
>
> Can anyone help me determine what I should recommend? If this were are
> masonry wall of a building, a retaining wall or such, I would install
> the ties or horizontal steel without question. Here it poses a problem
> for the contract who believes it will interfere with his mortar
joints.
> I don't think this would unless the block he is using locks which I
> could not see from the photos he provided. I am waiting for a shot
from
> the top down to see if there would be room to install #3 ties.
>
>
>
> TIA
>
> Dennis S. Wish, PE
>
>


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