I've had my tower up for years with $12 ones from the tractor supply. I'm no
engineer but they seem fine embedded in concrete.
I can't imagine the Rohn ones wouldn't hold up to much much more.
> On Jul 10, 2014, at 8:51 PM, Alfred Watson via TowerTalk
> <towertalk@contesting.com> wrote:
>
>
> I have always been told that (4 foot) earth screw in anchors (Rohn) are for
> very small and short towers . 20 G type.
> Is this correct now a days ?
>
> Al
>
>
> -----Original Message-----
> From: towertalk-request <towertalk-request@contesting.com>
> To: towertalk <towertalk@contesting.com>
> Sent: Thu, Jul 10, 2014 7:39 pm
> Subject: TowerTalk Digest, Vol 139, Issue 18
>
>
> Send TowerTalk mailing list submissions to
> towertalk@contesting.com
>
> To subscribe or unsubscribe via the World Wide Web, visit
> http://lists.contesting.com/mailman/listinfo/towertalk
> or, via email, send a message with subject or body 'help' to
> towertalk-request@contesting.com
>
> You can reach the person managing the list at
> towertalk-owner@contesting.com
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of TowerTalk digest..."
>
>
> Today's Topics:
>
> 1. How do bldg inspectors handle screw in earth anchors?
> (Richard (Rick) Karlquist)
> 2. Re: How do bldg inspectors handle screw in earth anchors?
> (Jim Lux)
> 3. Re: How do bldg inspectors handle screw in earth anchors?
> (Brian Amos)
> 4. Re: overhead truss for 80M rotary dipole (Chuck Gerarden)
> 5. Re: How do bldg inspectors handle screw in earth anchors?
> (Richard (Rick) Karlquist)
> 6. Re: How do bldg inspectors handle screw in earth anchors?
> (Mickey Baker)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 10 Jul 2014 10:29:40 -0700
> From: "Richard (Rick) Karlquist" <richard@karlquist.com>
> To: towertalk@contesting.com
> Subject: [TowerTalk] How do bldg inspectors handle screw in earth
> anchors?
> Message-ID: <53BECD84.7040802@karlquist.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Has anyone had experience getting a building permit
> for a tower with screw in earth anchors? How does
> it get "inspected". There is no empty hole for
> the inspector to look at. Do you show him the anchor
> before insertion? If you have an authorized AB
> Chance installing contractor put in the anchor,
> do they issue a certificate that you can show the
> inspector? In a sense, this contractor is also
> the engineer and building inspector all in one.
>
> Rick N6RK
>
>
>
> ------------------------------
>
> Message: 2
> Date: Thu, 10 Jul 2014 13:21:50 -0700
> From: Jim Lux <jimlux@earthlink.net>
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] How do bldg inspectors handle screw in earth
> anchors?
> Message-ID: <53BEF5DE.8020406@earthlink.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
>> On 7/10/14, 10:29 AM, Richard (Rick) Karlquist wrote:
>> Has anyone had experience getting a building permit
>> for a tower with screw in earth anchors? How does
>> it get "inspected". There is no empty hole for
>> the inspector to look at. Do you show him the anchor
>> before insertion? If you have an authorized AB
>> Chance installing contractor put in the anchor,
>> do they issue a certificate that you can show the
>> inspector? In a sense, this contractor is also
>> the engineer and building inspector all in one.
>
> could it be more like a material and process inspection?
> You have the paperwork showing you have the anchor and the mfr's
> paperwork showing what its properties are.
> Then you have paperwork showing you did the installation appropriately
> (e.g. if you used a truck mounted drive, it gives a reading of the
> torque as it drove it)
>
>
> The only time I've had an "official" inspection of a structure using
> screw in anchors it was for a temporary installation, and the guy came
> out, looked at the plans, looked at the erected contraption, verified
> that what we had built matched the plans, and said "go for it".
>
> Granted it was in an area and application where failure would hurt
> nobody but ourselves.
>
> What do utilities do when installing poles with these anchors? I find
> it hard to believe that the city sends out an inspector to watch them
> plant every pole and its guys.
>
>
> ------------------------------
>
> Message: 3
> Date: Thu, 10 Jul 2014 16:24:39 -0600
> From: Brian Amos <bamos1@gmail.com>
> To: "towertalk@contesting.com" <towertalk@contesting.com>
> Subject: Re: [TowerTalk] How do bldg inspectors handle screw in earth
> anchors?
> Message-ID:
> <CAO2gF474ZEZd1saK8KY35TyC0PAtDYMyjRmcjf5ziaNBNhu7yw@mail.gmail.com>
> Content-Type: text/plain; charset=UTF-8
>
> As for the utilities usually the municipality doesn't inspect their
> installations as they are self regulating. The "screw anchors" ie
> "helical piers" are installed to a certain torque which the software
> tells the installation contractor he must meet. As a soil engineer I
> have many times had to "inspect" the installation where I watch the
> pressure gauge and make sure they make it to the required pressure
> (which they tell me) for each pier and then I have to send a document
> to the owner stating that it complies with the design and put my stamp
> on it. I'm not a big fan of that setup as I don't do the engineering
> but I have to certify that it will hold up. It drives me nuts
> actually. For a residential purpose I would guess that you just tell
> the building official when you will be installing it and they can come
> and watch. That is the only way to really inspect them.
>
> BTW: Is this for supporting the tower? Or is it for the guys? If it's
> for the tower I suspect you will need at least one per leg and it must
> be a large tower to keep them at least 3 screw diameters apart to
> prevent interaction. This type of support provides virtually no
> lateral resistance (especially the square chance bars that have no
> soil contact anywhere but the helix, they are all tension and
> compression, so for guy supports they work great, but not so well for
> a foundation. I suspect that the building official won't care about
> inspecting screws for a guying system. They usually only care about
> the foundation itself.
>
> Brian
> KF7OVD
>
>> On Thu, Jul 10, 2014 at 2:21 PM, Jim Lux <jimlux@earthlink.net> wrote:
>>> On 7/10/14, 10:29 AM, Richard (Rick) Karlquist wrote:
>>>
>>> Has anyone had experience getting a building permit
>>> for a tower with screw in earth anchors? How does
>>> it get "inspected". There is no empty hole for
>>> the inspector to look at. Do you show him the anchor
>>> before insertion? If you have an authorized AB
>>> Chance installing contractor put in the anchor,
>>> do they issue a certificate that you can show the
>>> inspector? In a sense, this contractor is also
>>> the engineer and building inspector all in one.
>>
>> could it be more like a material and process inspection?
>> You have the paperwork showing you have the anchor and the mfr's paperwork
>> showing what its properties are.
>> Then you have paperwork showing you did the installation appropriately (e.g.
>> if you used a truck mounted drive, it gives a reading of the torque as it
>> drove it)
>>
>>
>> The only time I've had an "official" inspection of a structure using screw
>> in anchors it was for a temporary installation, and the guy came out, looked
>> at the plans, looked at the erected contraption, verified that what we had
>> built matched the plans, and said "go for it".
>>
>> Granted it was in an area and application where failure would hurt nobody
>> but ourselves.
>>
>> What do utilities do when installing poles with these anchors? I find it
>> hard to believe that the city sends out an inspector to watch them plant
>> every pole and its guys.
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
> ------------------------------
>
> Message: 4
> Date: Thu, 10 Jul 2014 18:33:12 -0500
> From: Chuck Gerarden <cgerarden@atomix.com>
> To: 'Markku Oksanen' <ww1c@outlook.com>
> Cc: towertalk@contesting.com
> Subject: Re: [TowerTalk] overhead truss for 80M rotary dipole
> Message-ID:
> <7eefd582140b841bfd9fb0f322cdba29f6031427@sitemail.hostway.com>
> Content-Type: text/plain; charset=UTF-8
>
> ?
> Markku,
> Thanks for all the great information. After reading responses I think
> my tubing is too small.I will also raise my truss height as suggested.
> Chuck
> W0DLE
>
> ----- Original Message -----
> From: Markku Oksanen
> To:"Grant Saviers" , "Chuck Gerarden" , "towertalk@contesting.com"
> Cc:
> Sent:Thu, 10 Jul 2014 07:00:43 +0000
> Subject:RE: [TowerTalk] overhead truss for 80M rotary dipole
>
> Hi
> Here at south OH-land (not Ohio) a dipole like this needs to start
> with 80 mm / 3 inch tubing with 3 mm walls. As tubing resistance to
> bending goes with 4th power of the outer radius, any extra mm is good.
> ?The tube at the truss attachment is 60 mm.
> Secondly, the compression (bending) caused by the truss wire
> increases proportional to 1/Sin(a) (or Tan(a), for small angles these
> are close) where the a is the angle between the element and the truss.
> This gets very quickly very large as we move to small (Sin(a) becomes
> small) angles between the element and the truss. ?So, moving the
> truss higher on the tower will help. ?
> I have a 100 foot home brew 80 m rotatable dipole and the truss is 3
> m/10 feet above. ?Truss goes to the 40% part and the ends are
> designed to stand the elements free of support. So, 40 feet out, 10
> feet above means a compression force ?4 x weight seen at the truss
> attachment point.
> I don't know what the accepted rule of thumb would be but if a
> truss-element angle of less than 15 degrees causes the weight of the
> element seen by the truss to be multiplied to a compression force of
> 4x the weight. This would be OK if the tube would be supported so that
> it can't bend under the pulling force. ?With no wind this is the
> case.
> For these reasons I believe there are three options: Increase of tube
> stiffness (diameter) so that the tube will be straight under all wind
> conditions (the part between the truss and the tower), move the truss
> higher to lower truss induced compression force or more difficult, add
> 2 more trusses so that they are 120 degrees around the element and
> prevent this bending and add more failure modes.
> I would move the truss higher, there is very little reason not to
> have it as high as you can (easier than changing anything else). The
> truss just about only is there the support the weight of the element
> and doesn't do much for sideways dynamic forces.
>
> MarkkuWW1C/OH2RA/OG2A
>
>> Date: Wed, 9 Jul 2014 22:36:15 -0700
>> From: grants2@pacbell.net [1]
>> To: cgerarden@atomix.com [2]; towertalk@contesting.com [3]
>> Subject: Re: [TowerTalk] overhead truss for 80M rotary dipole
>>
>> I rebuilt a tired EF180C (no longer sold) which is 86' long. Many
> of
>> the rivets were loose and were drilled out and replaced with cross
>> bolts. I particularly like W6NL's advice on connecting elements -
> two
>> bolts at 90 degrees which does reduce the movement in 2 planes.
>> Additionally he advises two guys above, so I use Phillystran to
> about
>> 20' out on each element. Mine are attached to a cross arm 4' above
> the
>> boom and about 30" each side, about what the linear loading wires
> were
>> originally. It is now tuned with a Tornado variable inductor and 25
> ohm
>> balun for full 80m coverage < 13:1. He also recommends a down guy
> to
>> the mast, then the antenna is totally constrained (I don't have
> one).
>> W6NL's view is that updrafts are likely and wind induced
> oscillations
>> can also move the elements vertically as you note, so a down guy is
>
>> important. This antenna might move to a higher more exposed tower
>> position and then I will add a down guy.
>>
>> I also ran the original (unguyed) design through YagiMech from DX
>> Engineering and that verified why there were some small bends. The
> wind
>> survival barely was above 70mph. With internal sleeving I was able
> to
>> improve that to almost 90mph. So far so good after 3 years,
> although my
>> wind conditions are very benign even at the 100' element height.
> btw
>> the tip elements are 1/4" diameter but the wind load is so small on
> them
>> they are not the weakest link.
>>
>> I think it is unlikely that an element will fail in column buckling
>
>> before failing in bending, and you are correct that guys load the
>> element in compression.
>>
>> Grant KZ1W
>>
>>
>>> On 7/9/2014 5:50 PM, Chuck Gerarden wrote:
>>> I have had several 80 meter rotary dipoles over the years and
> they
>>> have failed in the same manner due to very high windsthey get
> bent but
>>> never actually break. I wonder if the placement of the overhead
>>> element truss may cause this effect as thewind blows. The truss
> is
>>> pulling up on the element but as the wind blows harder, the truss
> is
>>> actually pulling on the element
>>> at an angle other than "up" due the the wind deforming the
> element.
>>> The harder the wind blows, the truss pulls the element harder
> into the
>>> mast.
>>> I am thinking the truss is too far out on the element and maybe
> it
>>> should be moved in closer. This changes the "pivot point"as the
> wind
>>> is hitting the element and the outer element area is moving more
> and
>>> the inner area is more stable.
>>> Is there a formula or does anyone have empirical knowledge on
> where
>>> the best place on an element or boom the truss should attach?
> Each
>>> element is 41' long for a total length of 82'. The antenna is
> center
>>> coll loaded for resonance and fed with a25 ohm balun.
>>> I of course could have 1 overhead truss and a side truss to
> resist
>>> horizontal forces, but I would prefer to keep it simple ifthe
>>> engineering allows it. This entire problem may be the aluminum
> tubing
>>> is not big enough or thick enough to beginwith. The elements
> start at
>>> 2 1/2 inches and taper to 1/2 inch.
>>> My latest solution is to use tapered 40' fiberglass poles as the
>>> elements with a wires inside. With big antennas I have often had
>>> better results after a wind storm since they return to their
> original
>>> position.
>>> Anyone out there have some good engineering advice on building 80
>>> meter rotary dipoles?
>>> ThanksChuckW0DLE
>>>
>>>
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk@contesting.com [4]
>>> http://lists.contesting.com/mailman/listinfo/towertalk [5]
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com [6]
>> http://lists.contesting.com/mailman/listinfo/towertalk [7]
>
>
> Links:
> ------
> [1] mailto:grants2@pacbell.net
> [2] mailto:cgerarden@atomix.com
> [3] mailto:towertalk@contesting.com
> [4] mailto:TowerTalk@contesting.com
> [5] http://lists.contesting.com/mailman/listinfo/towertalk
> [6] mailto:TowerTalk@contesting.com
> [7] http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
> ------------------------------
>
> Message: 5
> Date: Thu, 10 Jul 2014 17:37:55 -0700
> From: "Richard (Rick) Karlquist" <richard@karlquist.com>
> To: Brian Amos <bamos1@gmail.com>, "towertalk@contesting.com"
> <towertalk@contesting.com>
> Subject: Re: [TowerTalk] How do bldg inspectors handle screw in earth
> anchors?
> Message-ID: <53BF31E3.2010905@karlquist.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> The screw in anchors, if used, would be for guying.
> I guess you are saying that I must make the base big
> enough to handle lateral force and I can't use the
> guy anchors to hold the base in place. Got that.
> So I have a choice of having my engineer watch
> and certify and/or inviting the inspector watch
> himself.
>
> Is the pressure you are talking about the amount of
> force to push the anchor in (an axial force) or the
> amount of torque to turn the anchor in? With the
> hand installed ones, only torque is needed. The
> screw pulls itself into the ground.
>
> Rick N6RK
>
>> On 7/10/2014 3:24 PM, Brian Amos wrote:
>> As for the utilities usually the municipality doesn't inspect their
>> installations as they are self regulating. The "screw anchors" ie
>> "helical piers" are installed to a certain torque which the software
>> tells the installation contractor he must meet. As a soil engineer I
>> have many times had to "inspect" the installation where I watch the
>> pressure gauge and make sure they make it to the required pressure
>> (which they tell me) for each pier and then I have to send a document
>> to the owner stating that it complies with the design and put my stamp
>> on it. I'm not a big fan of that setup as I don't do the engineering
>> but I have to certify that it will hold up. It drives me nuts
>> actually. For a residential purpose I would guess that you just tell
>> the building official when you will be installing it and they can come
>> and watch. That is the only way to really inspect them.
>>
>> BTW: Is this for supporting the tower? Or is it for the guys? If it's
>> for the tower I suspect you will need at least one per leg and it must
>> be a large tower to keep them at least 3 screw diameters apart to
>> prevent interaction. This type of support provides virtually no
>> lateral resistance (especially the square chance bars that have no
>> soil contact anywhere but the helix, they are all tension and
>> compression, so for guy supports they work great, but not so well for
>> a foundation. I suspect that the building official won't care about
>> inspecting screws for a guying system. They usually only care about
>> the foundation itself.
>>
>> Brian
>> KF7OVD
>>
>>> On Thu, Jul 10, 2014 at 2:21 PM, Jim Lux <jimlux@earthlink.net> wrote:
>>>> On 7/10/14, 10:29 AM, Richard (Rick) Karlquist wrote:
>>>>
>>>> Has anyone had experience getting a building permit
>>>> for a tower with screw in earth anchors? How does
>>>> it get "inspected". There is no empty hole for
>>>> the inspector to look at. Do you show him the anchor
>>>> before insertion? If you have an authorized AB
>>>> Chance installing contractor put in the anchor,
>>>> do they issue a certificate that you can show the
>>>> inspector? In a sense, this contractor is also
>>>> the engineer and building inspector all in one.
>>>
>>> could it be more like a material and process inspection?
>>> You have the paperwork showing you have the anchor and the mfr's paperwork
>>> showing what its properties are.
>>> Then you have paperwork showing you did the installation appropriately (e.g.
>>> if you used a truck mounted drive, it gives a reading of the torque as it
>>> drove it)
>>>
>>>
>>> The only time I've had an "official" inspection of a structure using screw
>>> in anchors it was for a temporary installation, and the guy came out, looked
>>> at the plans, looked at the erected contraption, verified that what we had
>>> built matched the plans, and said "go for it".
>>>
>>> Granted it was in an area and application where failure would hurt nobody
>>> but ourselves.
>>>
>>> What do utilities do when installing poles with these anchors? I find it
>>> hard to believe that the city sends out an inspector to watch them plant
>>> every pole and its guys.
>>>
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
> ------------------------------
>
> Message: 6
> Date: Thu, 10 Jul 2014 20:38:46 -0400
> From: Mickey Baker <fishflorida@gmail.com>
> To: "Richard (Rick) Karlquist" <richard@karlquist.com>
> Cc: towertalk@contesting.com
> Subject: Re: [TowerTalk] How do bldg inspectors handle screw in earth
> anchors?
> Message-ID:
> <CAOB+T5atUqODHCqW23vx3LdcH62Ess4VaZ+B5rqQDP=K8ngsRg@mail.gmail.com>
> Content-Type: text/plain; charset=UTF-8
>
> As always, it depends. Some inspectors are more thorough than others, some
> municipalities have more or less stringent standards.
> These type anchors are commonly used as tie downs for manufactured
> buildings... like mobile homes. Typically there's a site inspection when
> the structure is delivered, and the tie downs are part of the package. At
> that time, they may be measured or manufacturer's tags inspected and
> recorded.
>
> After the structure is placed and the tie downs affixed, they're inspected
> at the attach point. The inspector has the option to have one dug up if he
> suspects funny business, but I've never seen it happen.
>
> Contractors can get into big trouble for submitting bogus tie down
> installations for inspection, not to mention liability issues.
>
> I have a family member who owns several trailer parks, and I've seen this
> process repeated many times. If you have a licensed contractor do it, you
> are likely to have no problem.
>
> 73,
>
> Mickey N4MB
> On Jul 10, 2014 1:29 PM, "Richard (Rick) Karlquist" <richard@karlquist.com>
> wrote:
>
>> Has anyone had experience getting a building permit
>> for a tower with screw in earth anchors? How does
>> it get "inspected". There is no empty hole for
>> the inspector to look at. Do you show him the anchor
>> before insertion? If you have an authorized AB
>> Chance installing contractor put in the anchor,
>> do they issue a certificate that you can show the
>> inspector? In a sense, this contractor is also
>> the engineer and building inspector all in one.
>>
>> Rick N6RK
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
> ------------------------------
>
> End of TowerTalk Digest, Vol 139, Issue 18
> ******************************************
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|