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Re: big dig structural failure - epoxy anchors overhead supporting gravity

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Chuck-

Great question!  Years ago when I served on the SEAOSC Ad Hoc Commttee on Testing Standards  I got to see John Kariotis pound on anchor suppliers about theses sorts of issues.  :)

Of course John was a big proponant of CIP anchors and (grudgingly) undercut anchors. 

Between the mini lectures that John gave & all the testing I did I learned a lot about why anchors work & fail.

Overhead installations got a LOT of attention; the mfr's pretty much just wanted to "wave hands" about installation means & methods. 

Nels- Thanks for suppling AC number AC58

John didn't like the AC58 protocol.....SEAOSC committee can up with a different one but back then the industry was using AC58.

Anyway.......John said that if they (chem anchor mfrs) wanted approval for overhead installation.....they better #@*! well install them overhead & then test them!  AND specify the installation means & method!  :)

I don't remember the outcome (or if there was one) but  I was glad to be "just the test guy"

It is possible (fairly easily) with some forthought & planning to install chemical anchors overhead but you have to provide a sealing mechanism & a means to support the rod until the chem gels.

For threaded rod, the method I came up with was.........

a plate washer supported by a nut at  a location on the rod that results in the desired rod projection
AND
a 1 x 2  "stick" cut the length such than with a slight compressive bow it will fit nicely between the tip of the anchor & the floor

with the hole cleaned & prepped;
inject the chem into the hole (starting deep & withdrawing as chem is dispensed)

when you reach the surface of the concrete witht he chem, push in the threaded rod / washer / nut assembly into the filled hole, rotating clockwise, counter clockwise slightly to distribute chem & pop any air bubbles.

when the washer seats, flex the stick, place it against the end of the anchor & you're done.

In a couple of hours & in many cases a several minutes the anchor can easily support itself; but this is chem & temperature dependent

Any attempt to hold anchors in place with duct tape, wire  or other "seat of the pants method" is to insure anchor installs of unkown fill.

cheers
Bob



On 7/16/06, chuck utzman <chuckuc(--nospam--at)pacbell.net> wrote:
So, how do you keep overhead exopy in place?
Chuck Utzman, P.E.


Nels Roselund wrote:
Christopher Wright wrote: " Just out of my own curiosity, does anyone ever
subject these items to cyclic loading or repeated sudden loads?"

ICBO Acceptance Criteria for adhesive anchors includes cyclic testing for
wind or earthquake resistance [see www.icc-es.org/criteria/index ; take a
look at AC58].

I wonder about the overhead installation -- freshly placed epoxyie have
fluid consistencies of various viscosities. Some may be difficult to keep
in place in an overhead hole while the anchor is being placed and during
cure.

Nels Roselund, SE
South San Gabriel, CA
njineer(--nospam--at)att.net -----Original Message----- From: Christopher Wright [mailto:chrisw(--nospam--at)skypoint.com]
Sent: Sunday, July 16, 2006 8:06 AM
To: seaint(--nospam--at)seaint.org Subject: Re: big dig structural failure - epoxy anchors overhead supporting gravity On Jul 16, 2006, at 12:47 AM, Robert Kazanjy wrote:
I think SImpson reudces their values depending on hole cleaning 
method, they even have a value for "no cleaning" but I'm sure there is
a huge scatter on those values & I'd be reluctant to use those values.
Just out of my own curiosity, does anyone ever subject these items to 
cyclic loading or repeated sudden loads? I'd expect that repeated loads
would reduce the capacity over time.

Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw(--nospam--at)skypoint.com | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania
1864)
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