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Re: UBC CODE INTERPRETATION

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> You should include seismic acceleration on the foundation when checking
> sliding of the overall structure (i.e., sliding force = 7.25 kip per your
> example). The earthquake motions are imparted to the structure at the
bottom
> of the foundation (via friction). The inertia of the foundation will try
to
> resist lateral movement, i.e. it doesn't know how to interpret the code,
it
> just reacts to acceleration (F=Ma).
>

It would also seem to be appropriate to include passive pressure of the soil
against the foundation to help against sliding.  I would not use the full
passive
pressure value though.  Apply an appropriate factor of safety based on your
knowledge of the soils.  Your geotech could help.  Also, you should call for
compaction of the soil around the outside of the foundation if you intend to
use passive pressure.  If sliding is that much of a problem, bury it down
deeper into the ground.

Dan Goodrich, P.E.


> > -----Original Message-----
> > From: Vinod Sahni [mailto:SAHNIVK(--nospam--at)nv.doe.gov]
> > Sent: Wednesday, December 06, 2000 9:29 AM
> > To: JLUTZ(--nospam--at)earthtech.com; seaint(--nospam--at)seaint.org
> > Subject: Ref: UBC CODE INTERPRETATION
> >
> >
> > Thanks for your reply.
> > But I probably got misunderstood or I did not clarify my
> > question enough.
> >
> > Basically, the question is this:
> >
> > Let us assume the following -
> >
> > Equipment Wt = 5 kip,  Accel at CG of Equipment = 0.65g
> > Foundation Wt = 10 kips, Max Ground Accel = 0.40g
> >
> > Let us calculate base shear for foundation sliding check:
> >
> > Sliding Force = 5 kip x 0.65 = 3.25 kip ( I believe this will
> > meet code).
> >
> > OR,
> >
> > Force = 5 kip x 0.65  +  10 kip x 0.40  =  7.25 kip (I do not
> > think code
> > requires this method).
> >
> > I would appreciate your looking into this further and giving
> > your opinion.
> >
> > Thanks again.
> >
> >
>
>