[TowerTalk] New Tower Old Base

[Grant Saviers]

All the numbers are in the 589 "Structural Analysis Report" 12/15/2010.  
Leave out whatever you like AYOR.  That's what makes lawyers rich.

Do not presume there are big safety margins in this design for the given 
wind spec.  My read of the calcs would indicate otherwise.  (nothing 
like 2 to 4x of a bridge, more like an airplane 1.3 to 1.5x).

Grant KZ1W

On 2/23/2011 7:07 PM, Kevin Normoyle wrote:
> the ability for a solid block foundation to resist overturning is 
> mostly dependent on the area of one side.
> So comparing volume is misleading, if you are willing to believe you 
> have sufficient soil for the concrete you have.
>
> People were willing to make all sorts of compromises for the drilled 
> anchor bolts, so why not compromise (or play it with less margin, 
> basically) on the concrete? If this is a permit situation, and someone 
> asks for calcs, it's obvious the numbers won't work for hardly any of 
> it. So this has to be a no-permit situation, or one where questions 
> aren't really asked.
>
> The manufacturer ships what, six 27" anchor bolts for this? Seems like 
> people were perfectly willing to go with less on the anchor bolts.
>
> the side area comparison is just 5.5 * 9 vs 3.5*5
> i.e. 49.5 sq ft vs 17.5..a 2.8x difference. That's within the range of 
> possible overdesign. So you can't say the existing foundation is 
> impossible to use. Just like you can't say any drilled anchor bolt 
> solution is guaranteed to fail.
>
> Now we don't know what kind of pullout force the anchor bolts need.
>
> But: if you're going to put in weaker anchor bolts (in resisting 
> pullout) than the original manufacturing spec, it makes sense that 
> your foundation only needs to be able to be good enough for your 
> anchor bolt setup.
>
> If people want to crank numbers, that's the set of numbers to crank: 
> what do you need for anchor bolts, to be able to overturn his existing 
> foundation. If you don't like that, then you shouldn't like it unless 
> there's a LOT of anchor bolts.
>
> What I don't understand, is why people jump on foundation sizes, but 
> easily look the other way when it's convenient or problematic (like 
> deep drilled anchor bolts).
>
> It's like we're amazing inconsistent on our engineering...yet we 
> pretend we're not.
>
> -kevin
> ad6z
>
> On 2/23/2011 4:15 PM, Grant Saviers wrote:
>> Actually, the current UST wet stamp calculations for my about to be
>> installed HDX589 has a base 5'6" sq by 9' deep. (10yds of concrete)
>>
>> MA-550 at 3.5 x 3.5 x 5'  is 2.3 yds so that is a VERY big difference.
>>
>> Grant  KZ1W
>>
>> On 2/23/2011 4:06 PM, Mike Fatchett W0MU wrote:
>>> Are you sure about the base?
>>>
>>> According to US tower the MA-550 requires a concrete base of:  3'6" x
>>> 3'6" x 5'
>>> The HDX-589 requires a base of:  5' x 5' x 8'
>>>
>>> That is difference of over 5 cubic yards of concrete.
>>>
>>> W0MU
>>>
>>> On 2/23/2011 4:35 PM, Richard Zalewski wrote:
>>>> First, thanks to all for their comments and suggestions.  Some details
>>>> omitted from my post:
>>>>
>>>> I will be replacing a Wilson MT61 (US TOWER MA550)that has the tilt 
>>>> base
>>>> fixture with a US Tower HDX589MDPL.  Both of these towers are self
>>>> supporting.  Both will have a SteppIR 3elment w/40m.  The existing 
>>>> concrete
>>>> base is more than adequate for either tower.
>>>>
>>>> I will continue to update as more information has been acquired.*
>>>>
>>>> HDX-589MDPL
>>>> **
>>>>
>>>> HDX-589MDPL
>>>> **
>>>>
>>>> HDX-589MDPL
>>>> *
>>>>
>>>>
>>>> On Thu, Feb 10, 2011 at 7:31 AM, Paul_group<
>>>> paul_group at greenrover.demon.co.uk>    wrote:
>>>>
>>>>> On 10/02/2011 13:53, pc2a at pi4cc.nl wrote:
>>>>>> Richard Zalewski schreef:
>>>>>>> I will be upgrading my tower and will be using my existing 
>>>>>>> base.  This
>>>>> will
>>>>>>> require drilling the existing concrete base and epoxing in some new
>>>>> bolts.
>>>>>>> I would be interested in exchanging some emails with someone who 
>>>>>>> has
>>>>> done
>>>>>>> this.
>>>>> Been using them for years, holding up masts on top of buildings, 
>>>>> railway
>>>>> overhead line gantries and all manner of structures.
>>>>>
>>>>> Take professional advice on the correct type to use - hilti are a 
>>>>> very
>>>>> good supplier.
>>>>>
>>>>> My 80' is attached to the block with them and I sleep soundly at 
>>>>> night....
>>>>>
>>>>> -- 
>>>>> 73 de Paul GW8IZR IO73TI
>>>>> http://www.gw8izr.com
>>>>>     _______________________________________________
>>>>>
>>>>>
>>>>>
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