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RE: Pool Seismic Loads

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That’s good advice Harold.  I agree.

In this case much of the water will slosh out and I hope they have a good drainage system.  With this kind of depth to width ratio most of it will be in the sloshing mode  but, without first doing the calculations, I would estimate that around 25+/- % should be considered as part of the seismic affecting weight.

Richard Hess, S.E.


From: Harold Sprague [mailto:spraguehope(--nospam--at)]
Sent: Tuesday, January 18, 2011 11:07 PM
To: seaint(--nospam--at)
Subject: RE: Pool Seismic Loads


You will not find a specific code reference for this.  It is just appropriate engineering design practice.  All sound engineering practice is not contained in the building code, nor should it be.  The building code is in a constant state of evolution as the practice of engineering evolves.  I design a lot of structures that are not contained in the building code.  Try to find how to design a boiler building containing a 36 million pound suspended boiler in the building code.  That does not preclude good engineering design.  Go back to the 1985 UBC and look at how nonbuilding structures were designed.  If prudent engineers would have only relied on the building code, many structures would not have been designed. 
Liquid of any type has 2 types of seismic induced forces.  The impulsive component 
represents the portion of the contents that move in unison with the swimming pool.  The convective component is the sloshing portion of the water.  AWWA D100 structures characterize both components for elevated water towers.  The ACI 350.3 also charachterizes both components. 

Regards, Harold Sprague


Subject: Pool Seismic Loads
Date: Mon, 17 Jan 2011 10:43:41 -0500
From: rstuart(--nospam--at)
To: seaint(--nospam--at)



I am looking at an existing 11 story concrete structure which will be converted to residential units with a new 100’x25’x4’ pool on the roof.  My greatest concern is the effect the pool will have on the lateral system.  My question is: do pools need to be included in the calculation of mass dead loads for seismic forces on the building?  If I look at ASCE 7-05, I’m lead to believe that pools are NOT dead loads but rather live loads (although the code does not explicitly state this).  I’ve also looked at ACI 350.3-01 (Seismic Design of Liquid Containing Concrete Structures), but this publication seems to be aimed more at the design of walls and floors containing liquids, not building lateral systems supporting pools as is my case.


I would appreciate if anyone knows of a SPECIFIC CODE REFERENCE addressing the issue.  I’ve already searched various other engineering websites and found that there are many opinions on the subject, but no solid answers.


Thanks in advance,


Ross Stuart
Structural Engineer, EIT

P 215.569.2900 Ext. 3381
F 215.569.5963