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Zone 4 Tilt-ups -- What to say to a Client

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Colleagues,

Is there anyone out there in list-land who is on or familiar with the
California Seismic Safety Commission and it's long-term plans in re
tilt-ups?

I have an architect/client with a business owner/customer who has retained
them to make initial conceptual studies in regard to the construction of a
high-tech fabrication facility at two alternative sites.  Both are in
existing tilt-up concrete buildings constructed, "around 1970."  I do not at
this point have documentation for either structure, but I know from limited
field observations that both have wood ledgers.  The architect's preliminary
assessment is that the proposed facility would be feasible (architecturally,
mechanically, and etc.) in either building, with some preference for what I
will refer to as Building B.

My problem is that Building A (the less preferred alternate otherwise) may
be the preferred alternate structurally.  It is in a city which has a
retrofit ordinance and has had a structural upgrade to improve its ability
to survive future earthquakes.  I know this because I was told
(documentation for the retrofit is supposed to be available, but I have not
yet seen it) and saw some of the retrofit ties during the initial site
survey.  I saw nothing to indicate that Building B has had a similar
retrofit.  The city in which it is located does NOT have a retrofit
ordinance, and the building department says that it has at the moment no
plans to adopt one.

It is possible that Building B relies on cross grain bending for out of
plane anchorage of some of its exterior wall panels (it is more likely that
it has some out of plane anchors, but that they are grossly substandard with
respect to post-Northridge code requirements).  The buildings are only a few
miles apart, both in California, both in UBC Zone 4 and relatively near
known active faults (subject to velocity and acceleration amplification
factors under the 1997 UBC), which is the current model code in both cities.
Neither show obvious external signs of existing earthquake damage or other
structural problems.

My general question is how to advise the client during this initial phase.
His customer (the business owner) likes building B and is inclined not to
worry about things that aren't going to cost him money right now.  If he
goes with Building B, he may lease space or buy the whole thing.  If A, he
will lease.  He is not likely to authorize the expense of document recovery,
review and structural analysis to find out how bad the problems with
Building B (or how good the retrofit at A) might be, he simply wants advice
on feasibility based on the limited available information.

Can anyone offer a clue of what might be coming down the pike in this regard
(e.g. California Seismic Safety Commission requirements that could force the
City where Building B resides to adopt a retrofit ordinance -- forcing the
customer to pay for an upgrade a year or two down the road if he buys it
now)?  I fear the owner may make a bad business decision, and want to make
sure that I give the architect appropriate advice on the issue.

Drew A. Norman, S.E.
Drew A. Norman and Associates
Consulting Structural Engineering
Pasadena, California


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