How hollow - pull test - stability tests - Wessolly - Brudi - Sterken

Eric Frei

Lots of PDf's and documents to read on tree stability testing.

Tree Consult

Also Sterken's PDF well worth the read attached, bit of an extract attached.

Attached Files

A Guide For Tree Stability Analysis.pdf (466.8 KB, 55 views)

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treefeller

Just come across this, Got some good information on their

fatdog

Also just came across this and here lately that is what I've been dealing with is hollowed out trees. So thanks alot.
fatdog

sustainability

what a joke I can't beleive this is still being conducted... Ken James has a lot to answer for... Let me shag your girl friend ..take your job ... ruin your furniture and see how stable you are afterwards. The test is a sham and invariably done incorrectly cause it says nothing about how a tree is loaded naturally.

Eric Frei

Ahem, what are you on about with this part?

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treeseer

The whole post was rather strange..."invariably incorrect"? Does the poster have suggestions on improvements?

Eric Frei

Who is Ken James and who/where does he work? How is he involved in any of this?

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sustainability

Sorry, may have had a red ned too many when I posted. My belief is that pull testing can undermine the structural integrity of a tree and loosen the trees hold in the soil inadvertently. I am not a proponent for this type of investigation.

treeseer

Mechanical stability of trees under dynamic loads -- James et al. 93 (10): 1522 -- American Journal of Botany

He gave a very entertaining talk at isa a few years ago; I never investigated the science as Don is referring to; interesting.

Eric Frei

Cool, I loaded up the PDFs. Kenneth James.

Heavy reading though and I haven't really digested it.

Attached Files

	MECHANICAL STABILITY OF TREES UNDER DYNAMIC LOADS by Kenneth James 2006.pdf (639.5 KB, 132 views)
	Dynamic-Wind-Loads-on-trees-2005-K.James.pdf (674.6 KB, 290 views)
	Presentation-Dynamic-Loading-of-Trees-2003-K.James.pdf (3.18 MB, 89 views)

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Sean Freeman

The picture that Don Ross posted of the hydro-excavation on one side of a Jacaranda at New Farm is a terrible example of malpractice...it is NOT an example of root crown examination.

Who ever approved the work order for that should have been able to provide the high pressure lance operator with clear instructions on how the work was to be carried out....and they should have ensured that the works were proceeding in the correct manner, in accordance with the specifications given to the contractors.

Hydro-excavation contractors understand how to cut into highly compacted substrates and vaccum up the sludge they create, they do not understand the biological and physical function nor anatomy of tree roots.

That is a very embaressing picture for BCC.

Eric Frei

Thanks Sean, I missed that picture. I have now embedded it here. It should go over to this thread too, I'll copy these 2 post over to there.
New Farm Jacarandas

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Sean Freeman

Some questions were asked early on in this thread about what impact the Static Integrated Assessment SIA (tree pulling) would have on the roots and soil of the tested tree.

Here is a brief and basic description of the technique that (I hope) will allay any fears about the consequences of carrying out such testing.

SIA is based on methods and research first published by G. Sinn and L. Wessolly back in 1989…it has never been held up as the single perfect method for all cases (in fact it has some strict limitations on how it can be applied) SIA was further refined and the approach refined in papers published by M. Erb and L. Wessolly in 1998.

It is an approach to assessing resistance to loading that is based on the behaviour of mechanical structures and systems used in engineering and the construction industry.

SIA incorporates two techniques;
1) Device supported approach
2) Visual assessment

The device supported approach is the tree pulling….its intention is to measure both the resistance to breaking and the resistance to tipping in the tested tree. It produces very exact data about the reaction of the tree to an artificially imposed load.

The tree has a line with a dynamometer attached (to measure the force applied)
o The change in the length of wood fibres in the outer parts of the stem are measured by an elastometer to 0.001mm over 250mm
o The change of angle of the stem base is measured by an inclinometer to 0.01 degrees



The test runs for approx 5mins, it is non-destructive and should be repeated with the elastometer and inclinometer placed in varying positions to ensure a comprehensive assessment is made.

The second step is the load analysis in the canopy….using a digital camera the canopy shape is drawn the spatial distribution is analysed in comparison to modeling of the wind distribution curve. The following are calculated…
o Centre of gravity of the tree
o Eccentricity of the crown
o Crown sail area
o The moment of wind load (at 32m/sec or force 12)

I do have some reservations about this second step…discussed below

The third step applies knowledge of the material properties of the green wood of the tree that is being tested. Extensive testing was carried out by Erb and Wessolly into the material properties of green wood of a great many of the commonly occurring tree species in northern Europe….this data is contained within the Stuttgart table of wood strength (Erb and Wessolly 1998) and forms the foundation of the calculations required to derive meaningful numerical values to the testing.

So what are the more significant problems with SIA?

• It cannot be used on forest grown trees with shared close canopies
• It is designed only to test whole tree, not individual limibs/unions
• It relies on modeling of drag coefficients through the canopy that are not currently able to represent dynamic resonance and dampening effects in actual trees.
• The baseline data for green wood strength properties does not currently include tropical species native to QLD
• The modeling is not capable of incorporating dynamic growth responses that are not static within the tree…this includes the pathogen host relationship.

Despite these limitations (that the original authors acknowledge) SIA has been used very effectively on individual trees of particular value to the community around them.

But to return to the original question relating to damage to the trees tested only one of the hundreds of trees tested has ever experienced root failure and this particular tree had its roots severed after the pull test.

The forces imparted to the tree are a fraction of the loading that even a minor storm would produce since all that is required is to produce a detectable reading in the two sensors related to a known load, to be able to extrapolate the results using the modelling.

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Eric Frei

We also have some contentious issues to consider here.

Results of tree-pulling (SIM) a possible fraud?

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newguy18

I still think pulling oin a suspected or confirmed rotten tree or a tree with bad roots is a bad idea,unless you want to break or move the root plate,possibly lead to major and minor cracks in the trunk or shift the soil and quite possibly weaken it.There is no way possible to tell about root or soil disturbance unless you air spade first which probabley wouldn't be a good idea when pulling.

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