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Re: Sloshing Damping

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There is nothing secretive about this. The formulae and graphs are documented in API codes. The forces are much reduced for large shallow tanks. 
----- Original Message -----
Sent: Wednesday, November 22, 2006 4:29 AM
Subject: RE: Sloshing Damping

I did several tank seismic calculations in the past using some complicated formulas developed by the petroleum industry to take sloshing into account.  In most cases it reduced the overall lateral force, but in some increased it from that of the 5% damped levels.  I don't know if any of these formulas are available for use beyond the petroleum industry however.  They were kind of secretive about them.

William.Sherman(--nospam--at) wrote:
It doesn't reduce your seismic shear.  Normally acceleration response spectra is based on 5% damping for buildings.  For sloshing water, the damping is reduced to 0.5%, which in turn increases the spectral response. The response at 0.5% damping is 1.50 times that at 5% damping.
Bill Sherman

From: Rich Lewis [mailto:seaint04(--nospam--at)]
Sent: Tuesday, November 21, 2006 3:07 PM
To: seaint(--nospam--at)
Subject: Sloshing Damping

ASCE 7 allows for 0.5% damping for sloshing of material in a storage tank.  How do I use this number to reduce the seismic shear?

Mark Pemberton, S.E.

Pemberton Engineering
502 Mace Blvd., Suite 2B
Davis, CA 95616

Ph:  (530) 792-0511
Fax: (530) 792-7109