[TowerTalk] windload rating of triex LM470e tower to be indep endently ver...

[Tower2sell@aol.com]

Hank,

In reference to UBC Table 18-I-A, look at the foot notes.

#2 allows for a 20% increase for each foot of depth or width up to a maximum of 3 times. Plus it references section 1612.3.2 that allows a 1/3 increase in allowable stress using a "wind" load. 

This means a Crystalline bedrock could go as high as
4000 x 3 x 4/3 = 16000 psf - quite a bit.

And for clay 16 feet deep:

1000 x 3 x 4/3 = 5333 psf still much greater than most geotechs would give.

Take full advantage of the code allowables, they are not that bad.

Something else to consider is that most (not all) catalog foundations are overdesigned by their nature of trying to work with multiple catalog towers. You can see this when the same foundation is specified for various towers with increasing foundation reactions. A simple suggestion is to specify the soil required for the specific catalog tower-foundation combination. Then one might be able to use the UBC tables.


Tower2sell@aol.com


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