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

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perhaps also, there is some ionic action?
With blow, you bring about a lot of electric ions, with brush, you
remove them with the brush?  like static electricity?

On 7/14/06, Robert Kazanjy <rkazanjy(--nospam--at)gmail.com> wrote:
Great photo, Steve.

The bolts w/ epoxy look pretty small in diameter!

Hole prep & concrete condition have an enormous effect on pullot loads.

A number of years ago I  tested 100's of "chemical" anchors (cyclic loading
protocol & cyclic loading to failure).  Hole prep was meticulous!

FYI  the Hilti hole cleaning method is brush, blow, brush.  Which I found to
be counter intuitive (but ultimately correct).

Being a rather curious fellow, did some holes where I used a "better"  (I
thought) cleaning sequence

brush, blow, brush, blow

this method resulted in very large reductions of pullout load

My hypothosis was that a "final blow" coated the hole with fine dust that
acted as a release agent, where as, a final brush mechanically removed the
dust thus exposing "clean" concrete to the epoxy.

If the bolts in the Big Dig installation were undersized to ease
installation or hole prep was skimped on..............

cheers
Bob


On 7/14/06, Gerard Madden, SE <gmse4603(--nospam--at)gmail.com> wrote:
>

Look at those 4 dinky bolts MAYBE 6" long total holding a thick WT with huge
clevis.... no wonder.

-g



On 7/14/06, Paul Feather < PFeather(--nospam--at)se-solutions.net> wrote:
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> Looks like the entire epoxy plug pulled clean with inadequate bond to the
concrete, not the bolts pulling clean without epoxy on them.
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> Paul Feather PE, SE
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> pfeather(--nospam--at)SE-Solutions.net
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> www.SE-Solutions.net
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> ________________________________

>
> From: S. Gordin [mailto:mailbox(--nospam--at)sgeconsulting.com ]
> Sent: Friday, July 14, 2006 11:56 AM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: big dig structural failure - epoxy anchors overhead
supporting gravity
>
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> Paul,
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> This is exactly how it looks.
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http://www.militaryphotos.net/forums/showthread.php?t=85890
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http://www.boston.com/news/traffic/bigdig/articles/2006/07/12/workmanship_and_design_of_tunnel_are_called_into_question/?p1=MEWell_Pos5
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> Steve Gordin SE
> Irvine CA
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> ----- Original Message -----
>
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> From: Paul Feather
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> To: seaint(--nospam--at)seaint.org
>
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> Sent: Friday, July 14, 2006 9:10 AM
>
>
> Subject: RE: big dig structural failure - epoxy anchors overhead
supporting gravity
>
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> <...> If the report is that the epoxy bolts pulled "clean out", it is most
likely the holes were not properly cleaned of drill dust and latent material
and the entire piece separated cleanly, bolt with epoxy and all.
>
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> Paul Feather PE, SE
>
> pfeather(--nospam--at)SE-Solutions.net
>
> www.SE-Solutions.net
>
>
>






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