[TowerTalk] windload rating of triex LM470e tower to be independently verified

[Al Williams]

Background:

On Aug 3 TexasRF on this post asked " ...if anyone had received a copy of
engineering calcs supporting the claim of ...24sqft/70mph for LM470E?".

On Aug30 FirstCall on this post wrote "The web pages and ads are 100%
correct in the stress analysis figures. Of those wanting a certified copy of
stress analysis it can be ordered from FirstCall directly."  The posting
also contained information about the re-start of the business of making
"Tri-Ex" towers with the LM470 now called the SkyTower470

My Experience:

On July 27 I received an Analysis package, three months after placing the
order and also requesting analysis for the countys 80mph requirement.  The
Analysis was dated May 2, 2000!!!!!!

Yesterday, after an hours long session with the county engineer and his
supervisor reviewing the analysis  I was informed that I would have to have
the tower and foundation analysis reviewed and certified by a Washington
State Professional Engineer.  I believe they were uncomfortable with the
analysis (copy including  stamped by a California State registered
professional engineer) because of the following:

  1.  The county engineers were informed several times that the California
engineer would call to discuss the      analysis but not call was received.

  2.  The Foundation Installation stated that "The tower footing design
shown is based on normal soil criteria...."  and "Normal soil is defined as
cohesive soil with an allowable vertical bearing load capacity of 4000
pounds per square foot".  The analysis contains a table listing various
soils.  The listing for 4000 pounds is defined as massive crystalline
bedrock !!!!!!!!

  3.  The county engineer asked several times who crossed out 70 and hand
wrote 80 for the wind speed and who crossed out 24 and hand wrote 15 for the
maximum antenna wind area.

  4.  The county engineer was also uncomfortable with the diagrams and
anaylsis of the rebar in the footing but I am not knowledgable to describe
this concern.

Summary:

In a week or two I will report on the findings of the Washington State
Professional Engineer.  Hopefully, it will substantiate the manufacturer and
FirstCalls rating claim; Further, that the new company, PARAGON MFG.,LLC
with help from FirstCall will be providing amateurs with a line of towers
and service at competitive prices.





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