Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Lateral decision

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Here is my opinion, for what it is worth.
1) Forget lawyers, your screwed any way you look at it. So do what your
engineering judgment tells you is most appropriate for the job.
2) You did not mention the materials of the building so I would assume that
you are not speaking about a URM building - which I would recommend that you
retrofit from top to bottom all at one time. I don't like to phase these
types of buildings as is allowed for financial consideration by the building
official since my personal opinion is that once you tie the building
together, you increase the chance of shear failure by ensuring a positive
connection of the diaphragm to the walls. By waiting three or six months to
install crosswalls and shear frames does not seem prudent to me. I have had
to comprimise on this issue, but I state my opinions in writing to my
clients to try and protect myself later.
3) We retrofit lightweight wood framed buildings all the time by stiffening
cripplewalls and improving connections of the builidng to the foundation. If
this is a wood framed building, I would not expect total collapse unless the
building were allowed to move off the foundation - HOWEVER, if it is a
public building that has, at any time, a high occupancy rate, I would push
for as much seismic upgrading as possible.

Remember too, if you analyze the builidng, you might find that wind governs.
In this case, you still need to bring as much up to better standards as
possible.

As far as your comment that it has performed okay up until now - it's only a
matter of time before conditions are right and the building is subjected to
just the combination of forces to do it damage. URM buildings survived in
Santa Monica for almost one hundred years until Northridge. Nobody can
predict when the time will come so your client is simply gambling with time.

Dennis Wish PE

-----Original Message-----
From: JRTCE <jrtce(--nospam--at)mbay.net>
To: seaoc(--nospam--at)seaoc.org <seaoc(--nospam--at)seaoc.org>
Date: Tuesday, February 03, 1998 9:33 PM
Subject: Lateral decision


>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 dont 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
>
>
>