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Re: Sloshing Damping
- To: seaint(--nospam--at)seaint.org
- Subject: Re: Sloshing Damping
- From: BCainse(--nospam--at)aol.com
- Date: Wed, 22 Nov 2006 10:06:58 EST
There are many good references out there on the simplifications API and
AWWA make for tank analysis. Google for such names as Lydik Jacobsen (sp?),
George Housner, Medhat Haroun among others. They describe the theory and
give you a feeling for the "code" equations in AWWA or API.
Bill Cain, S.E.
In a message dated 11/22/2006 5:30:35 A.M. Pacific Standard Time,
some sloshing calcs before too, using AWWA or APWWA ( I am not sure of the
acronym Water Association ) equations. Straight forward, but
For Damping, I don't know, I think your best bet might be to
model the whole water as a block of material, providing additional thrust mass
(or modeled in the density) due to the water. Maybe using the water with
very very small shear stiffness in a 3-D element. Then, run the static
analysis. Find the reactions at the tank, then put in an equivalent
spriing/damper at the location of the tank using your 0.5%
Maybe this will give you ideas.
On 11/22/06, Syed A
Masroor <masroor(--nospam--at)eaworld.com> wrote:
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 -----
Wednesday, November 22, 2006 4:29 AM
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
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%
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?
502 Mace Blvd.,
Davis, CA 95616
Ph: (530) 792-0511
Bill Cain, S.E.