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RE: Sloshing Damping

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Thanks all for your response.


As you can tell from my question I’m a little confused.  I’m designing a foundation for storage silos for plastic pellets.  I’m in the lowest seismic zone so I don’t think seismic will govern my design, but I want to check it.


ASCE 7-02 section is for elevated tanks for liquid and granular material.  It says to design by an approved standard or by section 9.14.5.  The table for approved standards doesn’t have a dry granular material standard.  I’m looking at section 9.14.5 and it gives a seismic shear value in equation  What I’m wondering is how sloshing affects this value.  Will it increase it or decrease it.  What damping is included in this shear value?  The commentary doesn’t appear to address it.








From: William.Sherman(--nospam--at) [mailto:William.Sherman(--nospam--at)]
Sent: Tuesday, November 21, 2006 4:21 PM
To: seaint(--nospam--at)
Subject: RE: Sloshing Damping


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?