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Re: Concrete vs. Steel

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     I've heard it said that "the faster you hit a speed bump - the smoother
it is."  Increasing the mass in a high seismic risk zone is like increasing
the speed - or - running on a hot day to get a breeze!

     Since thre is too much water in the mid-west and not enough in the
south-west,  the federal government should repo all of the concrete bridges
in the western state high seismic risk zones (and New Madrid area) and buy
the state owned ones.  They can then use them to construct a "V" or " \_/ "
shaped canal from the continental divide in New Mexico to Eastern
California.
     East of the continental divide, construct a CONCRETE box culvert (with
hydraulic lift) that extends to the Mississippi river with a branch into the
Arkansas river (Bill Clinton listening?) and a branch to the Gulf for
overflow.
     Tax the newly wealthy farmers in West Texas to Eastern California just
enough to reimburse the government for the new knee-braced, base isolated
tubular steel bridges that they have replaced the old ones with.
Then.......
     There won't be any houses floating off in the midwest, the Southwest
will be filthy rich, ACI will like the culvert and the West (and New Madrid)
will be another notch towards safe.

Greg
-----Original Message-----
From: Brennan Johnson <BJohnson(--nospam--at)eqe.com>
To: seaint(--nospam--at)seaint.org <seaint(--nospam--at)seaint.org>
Date: Friday, October 22, 1999 4:52 PM
Subject: Re: Concrete vs. Steel


>Wow, Greg, have you invited the flood gates to be opened here!  In
>California graduate structural engineering curriculums, courses are taught
>that focus exclusively on reinforced concrete ductile frames.  (An
>excellent text on this subject is "Seismic Design of Reinforced Concrete
>and Masonry Buildings" by Paulay & Priestley.)  Moreover, there are a
>number of design engineering companies in California that work almost
>exclusively in concrete; obviously they are able to do it efficiently, else
>they would not be in business!
>
>To extrapolate, as you have, and say that because concrete buildings
>collapsed in the recent Turkey earthquake we should not use concrete in
>seismically active areas is obscene.  Refer to the reports of the collapsed
>buildings in Turkey, and you will see that it was primarily poor design and
>construction that caused the failures:  poor and wrongly-placed lap splices
>and poor or no confining steel, primarily.  With each new earthquake,
>domestic or international, we certainly learn more about earthquakes and
>the limitations of our past designs.
>
>Regards,
>
>Brennan Johnson
>EQE International
>Irvine, CA
>
>
>
>     To be in charge of a project and prescribe the wrong material (even
>for
>economical reasons) is like a doctor prescribing the wrong medicine because
>the patient can't afford the right one.  In engineering as with medicine,
>this can lead to death.
>     I believe that concrete has been WRONGLY prescribed ANYWHERE in a high
>seismic risk zone.  The EQ's in Turkey, Bay Bridge, Japan etc. are obvious
>proof of this.  Yes, it is possible to construct a concrete structure that
>will withstand a Richter 10 but THAT would be UNeconomical.
>     Granted that Northridge revealed problems with steel and brittle
>fracture, it will be easier to overcome this than to take the mass out of
>concrete.  Concrete has it's advantages but only in a compatible location.
>Greg in Oklahoma
>
>
>