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Re: Sect 1632 Elements, Nonstructural Components & equip

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Equation 32-1 is the maximum design lateral force for a nonstructural component.
It is based on the worst location in the building, the worst dynamic
amplification, and the worst energy absorption capacity.  If your item is
relatively light, it may not be a penalty to the anchorage design.

If your item is heavy, it is better that you use the more precise equation 32-2,
which let's you insert actual values for location in building, dynamic
amplification, and energy absorption capacity.  Assuming that your safe is
located at grade, the parenthetical term reduces to 1.0.  With a-sub-p = 1.0,
R-sub-p = 3.0, C-sub-a = 0.66,  your design force should be 0.22 times W-sub-p.
That's a lot less than 2.64 times W-sub-p.

The answer to your question is that you may have missed something.  If you want
to use the quick-and-easy-to-use Eq. 32-1 instead of the more precise Eq. 32-2,
you may have to pay the anchorage penalty.  Sounds like you have an opportunity
to do a more precise calculation and save your client some money.

Rick Drake, SE
Fluor Daniel, Aliso Viejo


From: Steve Privett <eqretrodr(--nospam--at)> AT fdinet on 08/31/99 09:36 AM EDT

To:   seaint(--nospam--at) AT fdinet@ccMTA-fdlncta10
cc:    (bcc: Rick Drake/AV/FD/FluorCorp)

Subject:  Sect 1632 Elements, Nonstructural Components & equip

I'm working on the anchorage of a prefabricated "walk in" safe in So Calif and
have considered it a nonstructural component of the building, much like a piece
of equipment.  It is self supporting for vertical loads, and does not support
any aspects of the building it is housed in.

When determining the total design force (Fp)and using eq 32-1 of the 97 UBC I
get a substanially higher factor than using the comparable equation from earlier
codes.  The 97 code specifies Fp=4.0*Ca*Ip*Wp

Assuming a soil type of Sd and a seismic source type of A and a Near source
factor of 1.5, I end up with 4.0*.44*1.5*1.0*Wp or 2.64*Fp  This seems so much
higher than the older equation of ZICpWp which results in .8Wp at a worse case

Have I missed something here?  Are we really to anchor equipment now for forces
more than 3 times what the earlier codes required?

Steve Privett