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Lateral decision -Reply

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Your tale of retrofitting within economic means is often told. For this
reason, some retrofit standards allow the work to be done in stages. I
believe engineers have an obligation to educate building owners about
both the benefits and limits of seismic retrofit improvements. When
documented, such education should help limit the value of negligence
claims. As for the lawyer, you can point to the acceptance criteria for
retrofitting lateral-force-resisting-systems in UBC Section  3403

" Alterations of existing structural elements, or additions of new
structural elements, which are not required by Section 3401 and are
initiated for the purpose of increasing the lateral-force- resisting strength
or stiffness of an existing structure, need not be designed for forces
conforming to these regulations provided that an engineering analysis is
submitted to show that
1. The capacity of existing structural elements required to resist forces is
not reduced,
2. The lateral loading to required existing structural elements is not
increased beyond their capacity,
3. New structural elements are detailed and connected to the existing
structural elements as required by these regulations,
4. New or relocated nonstructural elements are detailed and connected
to existing or new structural elements as required by these regulations,
and
5. An unsafe condition as defined above is not created."

Hope this helps,

Tim McCormick. P.E.
City of Los Angeles

>>> "JRTCE" <jrtce(--nospam--at)mbay.net> 02/03/98 11:23am >>>
I am currently writing a proposal for engineering work on a two story,
early 1900's church. The owners would like to remove and relocate
some
first story walls. No work is proposed for the top story.  Both upper and
lower stories have significant seismic deficiencies from their original
design but have performed well so far. My proposal is for a seismic
retrofit of the first floor.  I am wondering if I should make it a
requirement of mine that retrofitting must be done on both the top and
bottom floors or I don't take the job.

On one hand, no work is being done up top and I am making the lower
floor
far stronger than it ever was so limiting my scope of work to the bottom
floor is acceptable. On the other hand, If there ever was a problem with
the upper floor the owner could say I was negligent in not making them
correct the upper floor problems. An attorney might also claim that I
changed the characteristics of the building and that led to an upper floor
failure.  I might also add that to retrofit the lower floor is relatively
easy but to retrofit the upper floor would be very difficult due to 20'
ceilings, alters, etc. and probably outside of the owners means. I would
be
interested in your comments.

Sincerely: Jerry R. Taylor