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Foundation Uplift Studies

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Priestly has done some work for Caltrans on this very issue.  Caltrans has
taken some of this information and generated subroutines that iterate
calculates to account for increased period of the structure due to rocking
effects (uplift of a portion of the footing). Unfortunately, these routines are
for in-house use or for consultants working for Caltrans.  If you know someone
who may have access to these routines, maybe they can share some background
reports or manuals.  Of course, this is not exactly the usual energy
dissipation/ductility concept building design is used to (R = ???).  It is more
a reduction to energy subceptability/ energy input.

In any event, some of the results and hinging of the footing concepts are
published in, "Seismic Design and Retrofit of Bridges" by Priestly, Seible and
Cavi, 1996, John Wiley & Sons. Check it out and see what you think.

ed gonzalez

>>> Mark Gilligan <MarkKGilligan(--nospam--at)compuserve.com> 05/19/99 10:56PM >>>
What is the R factor for a system where energy is dissipated through uplift
of the foundation?

I believe that this is a fairly common situation which occurs when you have
the minimum dead load required and at the same time when you have some
extra elastic capacity  in the lateral system.

Is it appropriate to use the R factor for an eccentrically braced frame
when the frame never yields because there isn't enough dead load to resist
uplift?

Is anybody familiar with the studies done on foundation uplift?

Mark Gilligan