[TowerTalk] Square Hole or Round Hole for Self Supporter?

[jimlux]

On 1/20/18 7:19 PM, john at 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 at 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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