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Re: Resultant Seismic Force

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I think:

you don't really know what the seismic forces are going to be anyway.

the tank is going on a dynamic ride of some seconds in duration, perhaps experiencing a pulse

consider adding more legs, if that's an option.

put a "safety factor" on whatever it is you don't want to fail, and don't get bogged down in believing you understand how the actual earthquake motions will affect the tank.

talk to a mechanical engineer, they design stuff for multiples of g everyday without cardiac arrest.

the seismic force is with you; but the devil is in the details.

James Bela

Oregon Earthquake AwarenessTM        /        The Quake NorthwestTM
"We Have Nothing To Fear But Shear Itself"        /        "We're All Subducting In This Together"

Vyacheslav Gordin wrote:


Vertical cryogenic vessel (tank) on three legs in seismic Zone 4.

Diameter:      4-to-10 feet
Shell height:  10-to-50 feet
Leg height:     about 2 feet

Weight:          15-to-150 kips.

Should the resultant of the seismic force be located at:
a) tank center of gravity; or
b) at 2/3 of the height?

The opinion of fellow professionals is crucial for me making the decision to
either accept the method ?a? (customary for the industry), or try to push
through method ?b? (as ? in my opinion - more corresponding to the physical
nature of the problem).

So, what do you think?

Steve Gordin, S.E.,
Irvine, CA

P.S. Anyway, if we have something as simple as a CMU property wall ? where
would you apply the resultant of the seismic force?  SG

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