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I misunderstood your needs.  What you are designing is a non-building
structure which is covered, by the Uniform Building Code and I would expect
any of a variety of other building codes.  The AWWA document will provide
you guidance on what the base shear and overturning moment at the bottom of
the tank are due to static loads plus convective and impulsive loads.  The
structure below is the "foundation" for your tank.  Applying the interface
loads between the tank and its "foundation" should get you in a reasonable
ball park.  The structure will largely behave as an inverted pendulum so an
equivalent static method should be a good start.

There was a suggestion that wall flexibility might be important, but I would
remind you that the precision with which we know the seismic or wind loads
is not high and the differences you will discover are probably still within
the margin of uncertainty of the loads.  Get the major effects right first,
then optimize if you feel the need.  But remember the sage advice of two

James Amrhein: "Don't be so precise that you forget to be accurate."


Aristotle: "It is the mark of an instructed mind to rest satisfied with the
degree of precision which the nature of the subject permits and not seek an
exactness where only an approximation of the truth is possible."

It sounds like an interesting project.  Good luck.

Bill Cain, SE
Oakland CA

-----Original Message-----
From: Juan José Treff De la Mora [mailto:jjtreff(--nospam--at)]
Sent: Tuesday, June 05, 2001 12:16 PM
To: seaint(--nospam--at)
Cc: bcain(--nospam--at); geeffland(--nospam--at)
Subject: RE: HIGH TANK

Thank you. Do those AWWA specs help you design the tank?  Because the tank 
is already completely designed in steel. I am just required to design the 
supporting structure that will put it 72 ft above the ground.

With earthquake (full tank) or wind (empty tank), that is an inverted 
pendulum. It has a body in motion inside. What I would like to know is how 
to structure the tower that will support the tank and if there are any 
simplified methods to solve it.

Thank you,


-----Original Message-----
From: Cain, William [mailto:bcain(--nospam--at)]
Sent: Martes 5 de Junio de 2001 12:22
To: 'seaint(--nospam--at)'
Subject: RE: HIGH TANK

You don't say which fluid but for water tanks try:
AWWA D-100-96 for welded steel tanks
AWWA D-103-97 for bolted steel tanks
AWWA D-110-95 for wire or strand wrapped prestressed concrete tanks
AWWA D-115-95 for prestressed concrete tanks with circumferential tendons
These can be ordered from AWWA at:

API has similar provisions for petroleum product storage.

Bill Cain, SE
Oakland CA

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