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Re: 'Epoxy creep' factor in Big Dig death

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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.


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 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

312.573.1726 facsimile
312.622.0409 mobile

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