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

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I agree - one other factor that I wondered about when I saw the detail:
It looks like the slabs were just sitting on the WT flanges.  Are there
any kind of bearing pads between the WT flanges and the concrete slabs?
I didn't see any in the diagrams or pictures I saw.  But if there are
not, what are the odds you get nice uniform bearing of the slab on the
WT?  Pretty slim.  Both the WT and the slabs are likely warped and
deflecting to some degree, each differently due to different
stiffnesses/shapes and materials.  So then with uneven bearing, you
could get an unanticipated distribution of load to the hanger rods,
perhaps exceeding the design load on one or more anchors.

Combine this with weak epoxy bond perhaps due to improper installation
as discussed before, and there's the potential for trouble.

Brian Harris, P.E.

-----Original Message-----
From: Robert Kazanjy [mailto:rkazanjy(--nospam--at)gmail.com] 
Sent: Sunday, July 16, 2006 1:03 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: big dig structural failure - epoxy anchors overhead
supporting gravity

I'll bet lunch at this point that it was poor hole prep, indequate
anchor size & questionable installation methods.are to blame;  failure
seldom results from a single error or bad practice........one needs the
cascade effect 

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