RE:Earthquake structures

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From: Raleigh McLemore (raleighmclemore@yahoo.com)
Date: Fri Oct 19 2001 - 20:29:51 PDT 

Message-ID: <20011020032951.65622.qmail@web13004.mail.yahoo.com>
Date: Fri, 19 Oct 2001 20:29:51 -0700 (PDT)
From: Raleigh McLemore <raleighmclemore@yahoo.com>
Subject: RE:Earthquake structures

Speaking as an elementary teacher I wanted to offer a
simple model that might be useful (I live in mortal
fear that some high school teachers must think we
simplify things too much, perhaps misleading instead
of teaching, but what the heck). I use the building
techniques in a book on "Building With Straws"
(actually I can't remember the exact title, but this
is close) to build simple house like structures.

I then put three identical structures in three
different aluminum cake pans. One pan is filled with
playdough, one with sand and one with potting soil.
Each is put on a cookie sheet. I then place the sheet
on wooden dowels I have sanded to a lobe-like shape.
Finally I move the cookie sheets gently forward and
back while students record and observe how the houses
react to the shaking motion. The house on the potting
soil usually falls first, proving that houses with
gardens are more dangerous...no, wait a minute, well
you get the idea. At the end of this part of the
experiment I pour a cup of water into each cake pan
and watch the potting soil "liquify" and the potting
soil house will fall without shaking.

The second part of the experiment is for students to
try to engineer their own "safe house", using straws,
a little tape and a sheet of paper, that can survive
the shaking. I encourage a written plan, then the
building, where students learn that written plans are,
uh, written plans. Then they build the real thing,
where paper is often used as thin rope like strands by
my 3-4 grade students.

Next to some simple pictures of shearwall on a house.
Talk about the observations of the original motion and
how shearwall might help. Students often box in their
walls with their paper shearwall and see improvement
in the structures ability to withstand shaking.

With firm handshake,
Raleigh

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