[TowerTalk] TowerTalk Digest, Vol 142, Issue 22

[Roger (K8RI) on TT]

On 10/14/2014 2:09 PM, Donald Chester wrote:
> Steve     K7LXC wrote:
>
>
>         >I'm not an engineer  but I can't find any validity in this
> statement. Bigger towers use the  pier-and-pin technique because it minimizes leg
> stresses on big towers  with microwave dishes which are kind of a non-issue

Originally, tower manufacturers sold "dirt bases" and had instructions 
for planting a tower section directly in concrete. The base tower 
section extended all the way through the concrete so it could drain 
properly.
I've not heard of these failing as the towers are designed to support a 
specif wind and weight load.
Yes the pier pin base is better if properly installed.  It's actually 
more difficult to properly guy a tower set directly in concrete, but not 
THAT much more difficult.

If not overloaded (a common ham practice) the tower should survive just 
fine set directly in concrete.  It's just that a properly installed pier 
pin base subjects the tower to less torsional forces,


> for your  typical amateur installation. There are tens of thousands of guyed
> towers with  the bottom section buried in concrete and the incidence of that
> failure mode is  non-existent in my experience.

I've seen a number of tower bases fail, but not because they were set in 
concrete.  It was because they had poor drainage, did not go all the way 
through the concrete causing water to collect in the legs and freeze. 
"spider webs in the legs", or a base that let water collect on the 
concrete around the legs causing the legs to rust through where they 
entered the concrete.

73

Roger  (K8RI)