On 1/20/18 7:19 PM, john@kk9a.com wrote:
I have round concrete bases on my all of my towers however they have guys
and pier pin bases so there is no torque on the concrete. With a free
standing tower there is torque, I guess you're saying that the ground
friction of a round section of concrete is sufficient to prevent the tower
from rotating?
Plenty, I would think. When you think of the rotation torque on a
stoplight with a arm cantilevered out over 4 lanes of traffic, and a 60
mi/hr wind blowing on it, that's a lot more than any ham tower is ever
going to see. I don't know what the design wind speed is in our area
for that kind of thing, but I'll bet it's fairly high, since we
*observe* 60 mi/hr gusts regularly during Santa Ana conditions.
John KK9A
From: jimlux <jimlux@earthlink.net>
Date: Sat, 20 Jan 2018 14:59:00 -0800
Nope.. Here in Southern California, there's a big business in drilling holes
to be used as foundations for things like traffic lights (huge bending
moment) - you can drill a 4 foot diameter 20 foot deep hole where the
sidewalk is, lower a rebar cage in, and fill it with concrete to make a very
solid pier for the traffic light to bolt to.
The whole "cube" is mostly because it's easy to dig by hand/backhoe, and
easy to calculate.
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