Gentlemen, many thanks for your kind assistance. Frankly, the range of
advice ranged from common steel is satisfactory to high strength steel
(grade 5 or the like) would be safer. I also talked to an engineer at
Valmont. (BTW, one class of their 1-1/2" anchors was equivalent to A307
spec material.) Nevertheless, he was reluctant to say that the common
threaded rod would be suitable without a structural analysis.
Finally, I got a hold of Carl Tashjian, current proprietor of Tashjian
Towers and former engineer for Tri-EX. I described the base plate and
installation plans and asked what grade of steel would be suitable for
the anchors. He said without hesitation "A307." So I'm sticking with
what I have already. However, I've asked the supplier to find out
whether the manufacturer is domestic or Chinese.
Thanks to all!
73, Joe
Jim Lux wrote:
>At 09:18 PM 9/13/2005, Richard (Rick) Karlquist (N6RK) wrote:
>
>
>>>I am installing an LM-470 and prefer to use a base plate for the tilt
>>>base that was designed for retrofit to an already existing concrete pad
>>>and anchor bolts. The base plate takes three 1-1/2" anchor bolts, which
>>>will be 27-36" long. I have purchased 10 feet of 1-1/2" threaded rod
>>>that meets ASTM specification A307A,B or C. Apparently, the stuff is
>>>known as "common" threaded rod and is the lowest strength available. Is
>>>this rod suitable for this application?
>>>
>>>Tnx and 73,
>>>
>>>Joe
>>>K2XX
>>>
>>>
>>It seems to me that the strength of the concrete limits the safe load
>>you can put on anchor bolts to a low enough value that ordinary steel
>>is good enough for the bolts.
>>
>>
>
>
>I was chatting with a structural guy a few months ago about things like
>chemical anchors for patio covers and the like (a low load
>application). Turns out that "taint necessarily so". The problem isn't so
>much the strength of even crummy grades of steel, even aluminum rod would
>be strong enough from a materials point of view. The problem but the
>uncertain quality of manufacturing in the threaded rod or bolts. Things
>like voids, cracks, or inclusions can raise problems because they cause
>stress concentrations. When Home Depot goes to the "lowest backyard forge
>bidder" in a third world country (or more properly, some consolidator who
>contracts with dozens of these little manufacturing plants) you run the
>risk that they just dump any old steel from the ship breaker in India into
>the melt, then rolled out the rods, rolled the threads, dumped it into the
>plating bath, and loaded it into the container. Unless the rod actually
>fell apart coming out of the machine, it's unlikely it was ever really
>checked. They literally cannot afford to do any process controls or
>inspections.
>
>You could either buy cheap stuff and inspect the heck out of it (something
>most hams don't have the equipment or patience for) or spend twice as much
>and get something that comes with the process controls and source
>inspection. (not saying that there's not bogus junk out there, and outright
>fraud, but it's less likely)
>
>_______________________________________________
>
>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.
>
>_______________________________________________
>TowerTalk mailing list
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>http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
>
_______________________________________________
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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