[TowerTalk] Pad and Pier for ROHN SSV. Pad and Pier Foundations
David Robbins K1TTT
k1ttt at arrl.net
Sat Jul 9 11:42:04 EDT 2005
I would be surprised if rohn had done specific foundation design unless it
was a very large tower for a very rich customer. That is usually left to
the buyer/installer to get a local engineer to do a soil survey and either
sign off on the standard drawings or do a design specific for the location.
David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
> -----Original Message-----
> From: towertalk-bounces at contesting.com [mailto:towertalk-
> bounces at contesting.com] On Behalf Of isp at bnjcomp.com
> Sent: Saturday, July 09, 2005 14:43
> To: towertalk
> Subject: [TowerTalk] Pad and Pier for ROHN SSV. Pad and Pier Foundations
>
>
> Of couse like everyone else here on this list that puts up thier own tower
> I am trying to save money. But also trying to stay safe. The property I
> am putting this on was originally part of a piece of land that was hopeful
> that the city would get a large business to be on. So for that reason
> they did core samples of the property. So I am going to try to acquire a
> copy of the results of those core samples to see what they say. So my
> question is I don't see in Rohn's book a spot for "if XXX sandy conditions
> then modify piers by doing this or that" or "if XXX compactness with clay
> then modify piers by doing this or that". Once I get that where do I
> look for those modifications. Also I tried when I bought this tower to
> get engineering drawings from ROHN but after MANY calls was unsuccessful.
> Does anyone have any new experience with new radian / rohn and think my
> ability to get those drawings would be better? Better question is it
> seems all the information is in the
> Rohn Catalog and I am wondering what I will get off of those drawings
> that is not in the catalog (since the drawings will probable be for the
> original owners Soil conditions).?
>
> thanks terry
>
> ----- Original Message -----
> From: Bob Gates
> To: isp at bnjcomp.com
> Sent: Saturday, July 09, 2005 2:04 AM
> Subject: Re: [TowerTalk] Pad and Pier for ROHN SSV. Pad and Pier
> Foundations
>
>
> Terry,
>
> Well, you've forced me to go look at my Rohn catalog, and I see where
> the problem is. The foundation dimensions for section 14 "assume" you
> have the other 13 sections on top of it. That's why such a massive
> footing design. Since you're only using 8 sections (7-14 I think your
> original note said), the footing requirements are much less. However, you
> can't use the dimensions for section 8 either because you have more weight
> and mass involved than if you were using sections 1-8.
>
> Now I gather you don't need a permit for this, otherwise you wouldn't be
> asking. But I would make a compromise between the section 8 dimensions
> and the section 14 dimensions. Install a square footing using the "Drill
> and Bell" option basic numbers. The dimensions would be about 12' deep
> and 5' square (the numbers for section 11). Forget the bell portion, just
> a square hole. Having said that, it might be difficult to keep the hole
> only 5' square while digging down 12', so you may wind up with a slightly
> larger hole, which is also okay. Just dig the hole, use the trackhole to
> drop in a modified expanded rebar cage, and fill it with concrete. Don't
> forget to keep the rebar cage off the bottom of the hole to prevent
> rusting over time.
>
> Hope this helps and GL,
>
> 73, Bob W7BJ
> ----- Original Message -----
> From: isp at bnjcomp.com
> To: towertalk
> Sent: Friday, July 08, 2005 10:03 PM
> Subject: Re: [TowerTalk] Pad and Pier for ROHN SSV. Pad and Pier
> Foundations
>
>
> Bob,
>
> Please rember that I don;'t know or have access to a belling machine.
> Makes me kind of paranoid to think about getting 10-12' in a hole and hand
> belling out hole. Are you suggesting a big square hole (have easy access
> to 70' trackhole but would have to hire someone out (like a well boring
> person in our area) if I wanted a "round" hole) that is size of recomended
> rohn pad at bottom of pier?
>
> IN my rohn bible book on page SSV-3 is where I am getting my specs.
> For a 14N section:
>
> 1. pier pad combo is 12' down with a 2' X 2' X 2' pad at bottom. 18
> yards of concrete
> 2. drill and bell is 14' down with a 6' bell 16.7 yards of concrete
> 3. drill is 25' down 27 yards of concrete.
>
> I am also thinking that all of these specs "assume" that you will have
> sections 6n - 1w which I don't so that should give me some relief.
> my concrete/tower guy wants to go 10' and put a massive pad at bottom
> of piers to give it weight.
> I am going to ask my trackhole person how much of a "bell" he can put
> at bottom of 14' with his trackhole. I mean the main hole is 3' right so
> that gives him room to go down and then scrap out 2' all way around right?
> Guys am I way off here?
>
> I only get to do this once so am looking for good input from this
> list.
>
> thanks terry
>
> ----- Original Message -----
> From: Bob Gates
> To: isp at bnjcomp.com
> Sent: Friday, July 08, 2005 1:39 AM
> Subject: Re: [TowerTalk] Pad and Pier for ROHN SSV. Pad and Pier
> Foundations
>
>
> Terry,
>
> Pardon the expression, but that is a hell of a lot of digging and
> concrete. Spent 30 years with a major oil company, most in Marketing
> Engineering. I was a region manager when the company was going through a
> cost cutting exercise, and the next thing I knew the drawings for our
> large canopies were revised to show these spread footings. I'm talking
> structures that were 48'x105'++. There were two columns every 25'
> lengthwise. Upon asking why the change, I was advised that the bell
> footings used less concrete, ergo less cost. When I pointed out that
> digging the bell, and forming out the rest of the hole so someone couldn't
> get buried if a wall fell in, actually increased the cost. The design was
> quickly changed back to a rectangular footing. BTW, the canopies had a
> wind rating of 110mph. Would suggest the same in your case. Either dig a
> rectangular hole the size of the bottom of the bell, or auger a hole the
> same diameter as the bottom. Spend a few dollars more o
> n co
> ncrete and save significant man hours. Net is a lower cost, and just
> as safe. If you feel uneasy about this, ask a registered engineer in your
> area. GL.
>
> 73, Bob W7BJ
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers",
> "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-
> 9041 with any questions and ask for Sherman, W2FLA.
>
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> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
> any questions and ask for Sherman, W2FLA.
>
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