Gary, I'm not a wind loading guru but previous posts have given the URL
to where the formula and method for calculating it can be had. Maybe
someone will chime in and save you a search through the archives.
What I wanted to say is that you might want to consider drilling into
big rocks to anchor bases, guys, or props. Another technique you might
consider is to borrow the method used to "anchor" fence posts when
conditions prohibit setting posts into the soil (which may be way too
rocky for normal techniques.) This same technique is used to build
barricades to keep rock slides off highways.
Essentially you form up a large 3D rectangle or whatever shape you need
with stout fencing material and fill it with rocks of manageable size
making a very heavy weight anchor. The ones I have seen along road sides
are filled with stones about half the size of a man's fist plus or minus
Rock size is so the rocks are too big to escape from the container
through the fence material and small enough to not waste space (maximize
weight.)
The fence posts I have seen are made of a fencing material in the shape
of a cylinder, filled full of rocks, and then capped with a lid of
fencing material. The various components of fencing material are tied
together with wire or what is known to some as "hog rings" which are
secured with special pliers made for the job (slip joint pliers will
work but are not as easy to use.)
Maybe some of the grounding gurus will suggest best practices for your
difficult circumstances.
Best of luck with your project.
Patrick NJ5G
On 8/30/2016 1:20 PM, Gary Smith wrote:
I'm having to play games with setting up eight, short, active
vertical elements on an incredibly rocky area. I am not able to drive
in ground rods, much less the base of the antennas. I'm coming up
with a plan to make wooden bases for them and hold them down with
rocks.
Since I live on the ocean's edge and have to contend with hurricane
force winds every so often, I'm trying to figure out the wind loading
of the verticals I'm considering. I'll buy the aluminum sections from
DXE and prefer to use larger sections just because of branches
falling at the marsh edge, as they always do. But thicker pieces will
have more wind loading and that is a problem.
If I use the thinnest configuration I'll have about 22 feet tall made
of .375, .5, .625 & .750 sections.
I asked what the wind loading would be and nobody I talked to was
able to give me a clue. Does anyone know a formula to figure the wind
loading of tapered elements?
Thanks & 73,
Gary
KA1J
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