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

[jimlux]

On 1/26/18 9:51 AM, Fred Keen via TowerTalk wrote:
> My Ryerson book is not handy, but there is some serious weight in a wide flange, say 8' or 10" web that is 20'0 long. And then there is consideration for the "fixed to ground" part.
> 


8" either 18.4 or 23 lb/ft (skinny web or thick web)

so 20 ft is on the order of 4000 lb.  you might not even need ground 
anchors<grin>

Actually, if your ground anchors are suitable, you could use lengths of 
antenna/tower truss for this. If the free standing antenna can take that 
bending moment at the base, then the same antenna component laid on its 
side can take the same bending moment.

I think this goes to the whole answer: There's a lot of ways to solve 
the problem other than a cube of concrete.


I've given a lot of thought over the years to the "strut braced" (or 
"flying buttress" if you will) approach, for rapid field deployment.

I've also looked into what professional riggers do for this kind of 
thing - you can rent large 5000 pound (approx) blocks of concrete with a 
big loop in the top you can anchor a guy to. Or a FIBC (Flexible 
Intermediate Bulk Carrier) which holds about a cubic yard of, say, 
gravel (which also weighs about 5000 lb).   You could buy a few yards of 
gravel in FIBCs, then sell it when you're done.

ANother approach is concrete K-rail/Jersey barrier - about 4000 lb, 10 
ft long, 24in wide and 32in tall, according to google.
Caltrans pays 0.46/hour per 20foot section - call that about $12/day, 
and the rental company will come out and place it for you.
Another place I found quotes $100/month per 20 foot stick.


For field day, perhaps....




> Fred KC5YN
> 
>      On Friday, January 26, 2018 9:41 AM, Grant Saviers <grants2 at pacbell.net> wrote:
>   
> 
>   Sure, outriggers work on trailer mounted crank-ups or pneumatic masts.
> Enough stiffness/strength in the outrigger and long enough and the need
> for mass or a hole in the ground goes away.
> 
> Grant KZ1W
> 
> On 1/26/2018 5:03 AM, Hans Hammarquist via TowerTalk wrote:
>>    I wonder if the old idea of using two 20 foot steel beams in an X configuration anchored to the ground with screw anchors would work.According to the script each anchor has a pull-up rating of 14,000 pounds. That wold result in a resulting 280,000 foot-pound torque which might be enough for a decent, self-supporting tower. I don't know if a buried or above-ground installation should be best. Buried makes inspection for corrosion damages hard while above-ground is a trip hazard.
>>
>>
>> I've never seen it implemented but believe an above-ground installation could be cheaper (depending on the price of the steel beams) than a buried cement lump. At least it would require a back-hoe. Just a thought.
>>
>>
>> Hans - N2JFS
>>
>>    
>>
>>    
>>
>> -----Original Message-----
>> From: jimlux <jimlux at earthlink.net>
>> To: towertalk <towertalk at contesting.com>
>> Sent: Mon, 22 Jan 2018 16:22
>> Subject: Re: [TowerTalk] Square Hole or Round Hole for Self Supporter?
>>
>> On 1/22/18 12:06 PM, Richard Thorne wrote:> Clay,> > I emailed a fella by the name of Jeremy.  He quoted me $2800 for a 10' > hole.> >  From the other post's on the subject probably a reasonable number. I'll > still research the back hoe method.  I'll bet will be less expensive to > use a back hoe and have the dirt hauled off (if needed).> generally that's the case.  Round piers are handy if you're already drilling them for some other reason, or if you have limited room on top (a 20 foot deep 3-4 ft pier will fit a lot of places)There's also other schemes - shallower and larger in plan, for instance.There have been discussions on this list a few years ago about a sort of X plan -essentially radial reinforced concrete beams - you could be pretty shallow, at the cost of having 10 or 15 foot "arms" sticking out.  There are lots of engineering alternatives - there's nothing "special" about the "cube" as a base.Or, if your self supporter isn't a "flagpole" and skinny - Tapered
>   to
>>    wers: HV transmission towers, Windmills and Rohn BX have a lot of taper.  I suspect that you don't need a lot of "foundation" under the feet for that - enough to keep the downwind leg from sinking, and the upwind leg from lifting.______________________________________________________________________________________________TowerTalk mailing listTowerTalk at contesting.comhttp://lists.contesting.com/mailman/listinfo/towertalk
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