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Fw: Concrete vs. Steel

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Greg:

A witty response to be sure, but it does little to support you previous
comment on the inappropriateness of R/C in high seismic areas.

I believe that you will find research data accumulated during the last 10 to
20 years that supports the position that R/C frames and walls can be
properly designed such that they have the necessary ductility to undergo the
large deformations imposed by a massive earthquake.

I would agree that the design of R/C for seismic is probably more
complicated than for steel structures, but this simply means that the
designer (and inspectors) must be knowledgeable and conscientious in the
application of their work.  What engineer worth his/her salt wouldn't be
doing that all the time?

I would also agree that a designer unfamiliar with the intricacies of R/C
seismic design should NOT attempt it, because R/C is not quite as forgiving
as steel.  If your point is that improperly constructed/designed R/C is not
likely to perform well during an earthquake, I can't disagree.  But I would
hasten to add that improperly constructed/designed steel would also not
perform that well.

However, getting back to the point at hand, I don't see the basis for your
statement that R/C should not be used in high seismic areas - New Zealand is
a very good example of just that situation.  The building owners, and those
engineers that designed the structures, would I'm sure be chagrined to find
that they have to tear down/retrofit all their R/C structures as you seem to
be suggesting.

Finally, as to your position that constructing R/C for high seismic
resistance would be uneconomical, I would again have to disagree.  Here on
Guam the hotel structures are almost all R/C (save 2).  Getting back to the
original point of the thread, our location and labor situation demands that
R/C dominates steel as the preferred construction material.  Based on what I
know about NZ, they also use quite a bit of R/C, and I really don't think
they would be doing that if it were as uneconomical as you seem to believe.

Anyway, my two cents.

T. Eric Gillham PE
GK2 Inc.
PO Box 3207  Agana, Guam  96932
Email - gk2(--nospam--at)kuentos.guam.net
Ph:  (671) 477-9224
Fax: (671) 477-3456


-----Original Message-----
From: Greg Smith <strusup(--nospam--at)gte.net>
To: seaint(--nospam--at)seaint.org <seaint(--nospam--at)seaint.org>
Date: Monday, October 25, 1999 2:50 AM
Subject: Re: Concrete vs. Steel


>     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