] [Thread] [Date] [Author]

["Sandy Pringle" <sandyp(--nospam--at)beachnet.com>]

At 11:40 AM 1/29/97 -0800, you wrote:
>Does anybody know what is the accepted inclination of 22-1/2 degree epoxy
>bolts in unreinforced masonry (upwards, downwards, sideways)?
>
>It seems like the most common practice is to install them downwards, but
>what do you do when the bolts are at the ceiling?
>
>Thanks in advance,
>
>Alexander (Sasha) Itsekson
>Huntington Design Associates

The Inspection Practices Committee has participated in the investigation of
the use of epoxy anchors since their beginnings in the early 1980's. There
are several reliable manufacturers of these adhesives with ICBOES and City
of Los Angeles(COLA) approval. COLA Guideline 3 was developed originally
for the quality control of the installation of the URM shear anchors which
necessarily encompassed the 22 1/2 degree installation. Guideline 3, first
revised in 1986 allowed for the installation of 22 1/2 degree anchors
upwards or downwards, not sideways, for either the grouted 2/1/2" cored
anchor or the epoxy type.

Subsequent investigation required the discontinuance of the grouted anchor
installed in an upwards direction due to the unreliability of the
installation procedure's quality, but it was found that the adhesive filled
screen tube used with the epoxy type system allowed encapsulation of the
adhesive in place so that the anchor could be installed before the material
ran back out of the hole, in most cases.  COLA Guideline 3 also requires
Continuous Inspection of the installation of ALL inclined or declined
anchors to further tighten the quality control, because under the higher
temperatures of summer, for instance, the viscosity is higher and the
material does, in fact, run. There are several ways commonly used for
resolution of this particular problem, the most significant of which is to
wait until early in the day when the ambient and material temperatures are
low enough not to be a problem!  It doesn't take a Brain Surgeon for some
of these solutions, fortunately, but experienced Inspectors have dealt with
or have Principals to whom they can turn for difficult situation solution
development who may, in fact, be calling you for suggestions or approval.

The quality of the installation is the responsibility of the Contractor and
steps he must take to ensure the quality of the installation vary from
Contractor to Contractor and, as far as we Professional Inspectors are
concerned, whatever can be shown to work is OK. Sometimes we can make
suggestions, but we must be careful not to take the responsibility for the
installation from the Contractor and, in most cases, can only make
suggestions. This isn't an arena in which there is a lot of guidance and
codes.  This does require Inspectors experienced or trained in the
vagueries, if you will, of URM Retro-fit to ensure conformance to the
spirit of your plan.  The COLA Research and ICBOES Evaluation Reports go a
long way toward clarifying and delineating each step of the procedures, but
then there are those cases......

As far as the testing of 22 1/2 degree anchors is concerned....5% Tension
Testing is what was specified when Hilti first came out with the C-20
system and was included in the procedure, but I'm afraid there aren't any
failures, and the City of Los Angeles has long since discontinued the
insistence of this type of testing although it is still on the books.  The
testing is a pull on the pre-bent bolt. Since the bend occurs at the face
of the wall, the test is really of the quality of the piece of wall within
which the anchor lies.  Certainly the anchor isn't going to snake out of
the hole like a piece of spaghetti if the adhesive is incorrectly mixed;
however it would show some movement since the hole is bigger than the
anchor itself.  

The use of the two component cartridge system and the static mixing nozzles
go a long way toward ensuring proper mixing, but it still takes an
experienced and trained, Certified Inspector to best ensure the
installation of your anchors and since the UBC in section 106 requires the
Engineer of Record to specify "the names of the individuals or firms
performing Special Inspection and the disciplines which they will inspect",
you now have the codified opportunity to do just that.  Specify the
Inspector.......

But that's another thread altogether and one, I might add, to which I warm
quite 
promptly.

R. Sandy Pringle 			    STRUCTURAL INSPECTION CONSULTANTS     
Sandy Pringle & Associates		    (800)598-1970    Fax(310)376-5294 
http://www.beachnet.com/~sandyp/index.htm    Hermosa Beach & Redondo Beach,
CA	

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