> Sorry Joe, but Rohn 45G and "pier pin" adds up to a guyed tower to me.
The discussion I had with the PE was about tower bases in general. In
*that* discussion we did not differentiate. However, since the Rohn
documentation states that the CB1G *must* be square, there must be a
logical reason. I would not attempt to use undersize concrete -
particularly when the concrete would not fully support the base plate
(BPC25G) for the pier pin installation.
73,
... Joe, W4TV
On 10/27/2011 1:36 PM, Pete Smith wrote:
> Sorry Joe, but Rohn 45G and "pier pin" adds up to a guyed tower to me.
>
> 73, Pete N4ZR
>
> The World Contest Station Database, updated daily at
> www.conteststations.com
> The Reverse Beacon Network at http://reversebeacon.net, blog at
> reversebeacon.blogspot.com,
> spots at telnet.reversebeacon.net, port 7000 AND now
> at arcluster.reversebeacon.net port 7000
>
>
>
> On 10/26/2011 7:47 PM, Joe Subich, W4TV wrote:
>>
>> > Does this apply to a guyed tower?
>>
>> Our discussion was about towers in general ... there was no mention
>> of guyed vs. self-supporting or single pier vs. multiple pier (e.g.,
>> Rohn SSV with its wide base).
>>
>> In any case, looking at the Rohn web catalog will show that CB1G is
>> specified for all heights of Rohn 25 - except the tallest at 110 MPH.
>> Two guy anchors are used in the three tallest 110 MPH designs and
>> those towers are specified for GB2G. CB1G is a 2' 6" x 4' 0"
>> square base ... CB2G is a 3'0" x 4' round base. The Rohn document
>> is quite emphatic that CB1G *must* be square.
>>
>> The trends are consistent in the 45, and 55 documents as well -
>> CB1G may be used for the shortest towers but must be square. Larger
>> round piers are specified for taller towers and those with higher
>> wind ratings. Even the smallest of the 65 towers start with CB2G.
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>>
>> On 10/26/2011 5:21 PM, Pete Smith wrote:
>>> Does this apply to a guyed tower? I can understand big overturning
>>> forces in a self-supporter, but most of the forces acting on a guyed
>>> tower base are vertical, aren't they?
>>>
>>> 73, Pete N4ZR
>>>
>>> The World Contest Station Database, updated daily at
>>> www.conteststations.com
>>> The Reverse Beacon Network at http://reversebeacon.net, blog at
>>> reversebeacon.blogspot.com,
>>> spots at telnet.reversebeacon.net, port 7000 AND now
>>> at arcluster.reversebeacon.net port 7000
>>>
>>>
>>>
>>> On 10/26/2011 5:10 PM, Joe Subich, W4TV wrote:
>>>> I asked the same question of a well known Professional Engineer a
>>>> couple of years ago. His answer was quite simple and made a lot
>>>> of sense ... the round base can be used instead of a square one
>>>> if the diameter of the round base is the same as the *diagonal*
>>>> measurement of the square base.
>>>>
>>>> In your case, for a 2' 6" (30") square base the round equivalent
>>>> would be 42" diameter *not* 36" as you propose. The reason has to
>>>> due with projected surface area - the area that resists overturning
>>>> - not volume (or weight) of the concrete.
>>>>
>>>> 73,
>>>>
>>>> ... Joe, W4TV
>>>>
>>>>
>>>> On 10/26/2011 1:28 PM, Richard Thorne wrote:
>>>>> I'm finally getting some dirt work done in the next day or two at
>>>>> my new
>>>>> place which will include holes/concrete for my 45g tower.
>>>>>
>>>>> I plan on using a pier pin install, so does it matter if the base is
>>>>> square or round? The rohn book calls for a 2' 6" square hole 4' deep
>>>>> (I'm designing the tower based on 90mhp winds with a height of 120').
>>>>> It would be easier to use a 36" auger to dig the hole. Since I'm going
>>>>> with a pier pin I don't see that there would be any twisting
>>>>> moments on
>>>>> the concrete base, it would only be there to hold the tower up. But
>>>>> I'm
>>>>> not an engineer, hence the question.
>>>>>
>>>>> Thanks
>>>>>
>>>>> Rich - N5ZC
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> TowerTalk mailing list
>>>>> TowerTalk@contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>>>
>>>> _______________________________________________
>>>>
>>>>
>>>>
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>>>>
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>>>
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>>
>>
>
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