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Re: 'Epoxy creep' factor in Big Dig death

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I would agree with both David & Jordan.

I would caution list members about getting their information from the
newspaper (any newspaper)......how often do we read articles that are
filled with errors on topics we are familiar with?

I've tried to determine an online  source for the full test of the
NTSB report but have not been successful.

I'm sure that there is more to this than the newspaper & online "sound
bites" quoted from the NTSB reps & report.

Like most catastrophic failures, there was probably a string of
mistakes (in hindsight) that contributed to the outcome.

cheers
Bob

On 7/11/07, Jordan Truesdell, PE <seaint1(--nospam--at)truesdellengineering.com> wrote:
Actually, that was my thought as well.  I remember reports that the
epoxy anchors came out clean (well, dusty) with the epoxy intact around
the anchor. Also, the loading wasn't static due to the traveling
pressure waves in the tunnel.  To be honest, I rely on the manufacturers
data for installed anchors. If there are no specific limitations for
installation geometry or load cycling in the literature or ES report, I
generally presume that the  anchor is good for the rated load. While we
can all think of "better" (usually more expensive) ways to create a
detail, part of engineering is to produce the most economical solution.
If not, we could just go specify based on conservative rules of thumb,
like the prescriptive codes use.

Granted I have not read the report (and probably won't get to, to be
honest), but I'm not quite ready to cast stones.

Jordan



David Fisher wrote:
> This was certainly a terrible tragedy.
>
> But, as I understand it, epoxy anchors typically have a safety factor of at
> least 4:1.
>
> If it were really "epoxy creep" then why didn't more panels fail?
>
> I guess my point is that maybe the installation was faulty; perhaps the hole
> was not cleaned out or the epoxy incorrectly applied, etc.
>
>
> I think we can all look back at details we've done over the years and wonder
> "what was I thinking?"
>
> I think it could be classified as "seemed like a good idea at the time"
>
> Obviously, some sort of redundancy should have been built into the design;
> but say the panels were supported by four rods; at 4:1, the panel should
> have only needed ONE rod to support its dead weight...at least the panel
> would have come loose and repairs been able to be made to stabilize it prior
> to failure.
>
> It appears that there might be more to this story...
>
>
> Still, an awful waste of human life.
>
>
>
>
> David L. Fisher SE PE
> Senior Director
>
> Cape Cod Grand Cayman Holdings Ltd. - Cayman
> Fisher+Partners Structural Engineers Ltd. - Cayman
> 372 West Ontario Chicago 60610
> 75 Fort Street Georgetown Grand Cayman BWI
> 319 A Street Boston 02210
>
>
> 312.573.1701
> 312.573.1726 facsimile
> 312.622.0409 mobile
>
> www.ccgch.com
> www.fpse.com
>
>
>
>

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