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Re: FALLING ICE

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If a +ACI-large glacial like chunk of ice+ACI- is forming on the upper roof, I would
suggest you extend your investigation beyond the impact load on the lower
roof.

This sounds abnormal, even with a sixty foot annual snowfall.  I would
investigate the insulation and venting in the area where the ice dam is
forming and possibly help alleviate the problem from the formation end as
well.

just a thought.

Paul Feather PE

----- Original Message -----
From: Randy Vogelgesang +ADw-rvogel+AEA-jps.net+AD4-
To: +ADw-seaint+AEA-seaint.org+AD4-
Sent: Thursday, May 27, 1999 9:40 PM
Subject: Re: FALLING ICE


+AD4- Neil,
+AD4-
+AD4- This topic is along the lines of a problem that I will soon have to
address.
+AD4- Several months ago Kirkwood Ski resort called me to look at a roof that
had
+AD4- a failure.  It seems that a large glacial like chunk of ice (rough guess
10
+AD4- tons) fell about 20 feet from an upper roof and shattered some rafters at
+AD4- the front of the general store.  It turns out this is the second time that
+AD4- this has happened.
+AD4-
+AD4- A little aside, it seems that architects rarely listen to warnings
+AD4- explaining all the possible affects of sixty feet of annual snow fall.
+AD4-
+AD4- The lower roof was originally 3x6 rafters at 2' oc spanning about 5'.  The
+AD4- first time they failed they replaced them with 4x6 at 2'oc.  Five or six
of
+AD4- these 4x6's at the impact area were reduced to splinters.  The snow load
at
+AD4- this area (Pf) is 300 psf, the funny part of the story is that this roof
+AD4- never has any snow on it.  The upper roof tends to acculimate snow at an
+AD4- adjacent valley area and then gradually creep until it eventually falls to
+AD4- the unloaded roof below, then bounces off and lands in the parking lot.  I
+AD4- gave Kirkwood a temporary repair last the winter, and told them to call me
+AD4- this summer for a permanent repair.  I think that I will have fun trying
to
+AD4- come up with a reasonable but safe impact load for the new roof.
+AD4-
+AD4- Randy Vogelgesang S.E.
+AD4- South Lake Tahoe
+AD4-
+AD4-
+AD4-
+AD4- -----Original Message-----
+AD4- From: nmoore+AEA-innercite.com +ADw-nmoore+AEA-innercite.com+AD4-
+AD4- To: seaint+AEA-seaint.org +ADw-seaint+AEA-seaint.org+AD4-
+AD4- Date: Thursday, May 27, 1999 8:22 AM
+AD4- Subject: RE: FALLING ICE
+AD4-
+AD4-
+AD4- +AD4-Ah yes, when it shatters, it some times destroys the wall next to it+ACE-
+AD4- +AD4-(as told to me by some people in the Lake Tahoe area where the ice only
+AD4- +AD4-dropped twenty feet)
+AD4- +AD4-
+AD4- +AD4-Neil Moore, S.E.
+AD4- +AD4-
+AD4- +AD4APg-I think you can safely assume it is +ACI-dissipated+ACI- by shattering.
+AD4- +AD4APg-
+AD4- +AD4APgA+- -----Original Message-----
+AD4- +AD4APgA+- From: Michael O'Neil +AFs-mailto:moneil+AEA-f-w.com+AF0-
+AD4- +AD4APgA+- Sent: Wednesday, May 26, 1999 2:14 PM
+AD4- +AD4APgA+- To: SEAINT (E-mail)
+AD4- +AD4APgA+- Subject: FALLING ICE
+AD4- +AD4APgA+-
+AD4- +AD4APgA+-
+AD4- +AD4APgA+- I AM LOOKING FOR INFORMATION ON THE IMPACT FORCE FROM ICE
+AD4- +AD4APgA+- FALLING FROM A TOWER OR TALL BUILDING AND HOW THIS FORCE IS
+AD4- +AD4APgA+- DISSIPATED.
+AD4- +AD4APg-
+AD4- +AD4APg-
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