[CANUFNET] Hand pull testing

[Michael Richardson via CANUFNET]

Have you read all the papers describing the "scientific" methods and
foundational physics, structure and mechanics by people such as Sinn,
Wessolly, Detter, Brudi, van Wassenear, etc. plus the background found in
the Tree Statics book?

Further there are a number of calculators available online from Frank
Rinn, Brudi and Associates, and Argus.  A photograph of the canpoy profile
helps to determine the forces.

I think when you read these papers you will find that pulling on a tree
with a throwline will not replicate the forces (of a winch) nor will your
eye measure the micro-millimeter changes that the Elasto-inclino
methodology does.

I am not sure where the idea of pulling on a string where the greatest
force you can apply is essentially the same as your weight (remember
Newton's second law) can tell you too much about a tree. If the tree is
rocking at the root plate with your less than 200 pound force (again body
weight, Newton's Second and splitting of forces due to angle) than it is
clearly unstable, if the tree is not visibly moving does this mean
anything?

Good Luck

Michael


> Hi All,
>
> Does anyone have any data or guidelines for replicating a force on a tree
> when performing a hand pull test? As part of our advanced risk assessment
> techniques, we will perform a hand pull test on smaller trees to assess
> soil, root or trunk movement. We're curious as to the amount of force
> necessary to adequately represent a wind speed of up to 80 km/h. Any
> information on this subject would be appreciated.
>
> Thanks,
>
> ROB RENY | COORDINATOR, URBAN FORESTRY
>
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