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RE: Ice Force on Steel Water Storage Tanks

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Basically, you need to be able to resist 100% of the expansion force of the
ice.  This means you have to break the ice in compression.  Compressive
strength of ice is about 375 kPa (54 psi) just at freezing temp, and up to
1500 kPa (217 psi) at very cold temperatures.  

You can see why people in Canada empty their pools in winter!

A technique I've seen used in some warmer parts of Canada is to toss a log
or two into the pool and tie it/them so that it remains near the centre.
This provides an "expansion joint" of sorts as the ice can ride up on the
log.  The only catch is if the ice freezes thick enough that it gets solid
right under the log.

If you are using an open top storage tank, what about a "pond" with sloped
sides?  No lateral forces at all to deal with when the surface freezes.

Paul Meyer
250-368-2407
pmeyer(--nospam--at)hasimons.com

> -----Original Message-----
> From:	Ed Marshall [SMTP:elmarshall(--nospam--at)HASimons.com]
> Sent:	Tuesday, March 09, 1999 01:44 pm
> To:	'seaint(--nospam--at)seaint.org'
> Cc:	Bill Thornton
> Subject:	Ice Force on Steel Water Storage Tanks
> 
> A Question:
> 
> If the water in an open top steel storage tank were allowed to freeze,
> what
> lateral force would the ice exert on the tank shell?  Is this a practical
> condition to permit?  We're thinking of 10 to 15 foot diameter tanks
> located
> in cold climates.
> 
> I've checked AWWA D100 and didn't see this possibility addressed.  The
> dynamic ice pressures mentioned in the AASHTO code (for design of bridge
> piers) are in the range of 100 to 400 psi.  Such pressure would exert huge
> hoop stresses on a tank shell if a significant depth of water froze.
> Perhaps when the water is free to expand vertically as it freezes, the
> lateral pressures are much less.  Any comments would be appreciated.
> 
> Ed Marshall, P.E.
> Atlanta
> 
>