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Re: Seismic Loads on Electric Equipments

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Such equipment when placed on foundation normally have ZERO time period 
and thus can be treated as rigid mass. No special seismic analysis is 
necessary. However, if placed on an elevated structure the behaviour 
would be very different.


RP Mehrotra
Manager (Engg-Strl)
Engineers India Ltd
New Delhi INDIA

----- Original Message -----
From: "raul labbe" <rlabbe(--nospam--at)>
Date: Tuesday, May 29, 2001 12:22 pm
Subject: Seismic Loads on Electric Equipments

> Dear fellow engineers,
> I would like to know of some criteria, regarding the 
> seismic loads to be considered for electric equipment
> and their components and attachements. Equipments
> of the kind encountered in outdoors substations, like
> brakers, reactors, etc.
> I have seen ( and currently used) some codes specifying
> seismic loading for these items, in the usual loads for
> 'Equipments and non-structural items' e.g.    Z I Cp W,
> with the lateral force factor Cp= 0.75 . ( SEAOC, it seems ).
> This yields a global seismic factor of say  0.36 in high seismicity
> areas.
> But I also have seen that tests, developed on some of these
> devices ( mostly those having porcelain components ) show
> very low damping, very short natural period. All of this, calling
> for the use ( according to some codes ) of global seismic factor
> in the range of 90 to 100 % g.  
> Does anybody know a more specific american code or recommendation 
> addressing these matters? ( Regarding this, I only know the 
> newzealand code ).
> I appreciate, in advance, your informations.
> Raul Labbé S.E.
> rlabbe(--nospam--at)

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