At 06:01 AM 6/1/01 -0600, n4kg@juno.com wrote:
>There has been a lot of speculation that the downward
>forces on the base plate would prevent rotation about
>a pier pin. I know of one example where I'm sure there
>was enough torque to rotate about a pier pin.
>
>N4AR has a pair of 200 ft R45 towers with the bottom
>sections in concrete. One of these towers has a 4 high
>stack of CC 4L20's. After a tornado passed by his QTH
>he was cleaning up around the base of the tower when a
>finger went down into a hole. The tower rotated enough
>to SHEAR OFF all 3 legs!
Seems to me that inserting a sheet of some engineering plastic material
with a relatively low coefficient of friction between the bottom plate and
the top of the concrete base might facilitate this sort of rotation.
Wouldn't do anything to help with bending, though.
73, Pete N4ZR
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