Rigging and tree defects

rskybiz

TreeHouser
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Fort White Florida
In a recent removal (latest round of work pics) and countless times before I have wondered should I rig it so the weight falls on the defect side or the non defect side. Often it amounts to what direction will load the spline of the tree (I hope that comes off right) maybe tension and compression side makes more sense.
I'll try to make a example.
tall stem, some lean to opposite side of a defect at about 30 ft with 30ft above defect. Negative rigging what direction should the piece go? Back so the stress is forced over the defect or the other way?
I hope what I'm getting at is clear as mud and I know most times the tree lends itself a clear solution but I'm curious of the science. I have another senerio if this one is not enough to get a discussion started.
Thanks
 
It sure seems like you would want to rig toword the defect, using the better wood on the far side to tension the load. Not sure what experience bears out, good question. :?

This might be a little extreme, but I thnk it illustrates what you're talking about. I would think you'd rig into the defect.

DSC04706.jpg

DSC04707.jpg
 
Interesting question! My first thoughts would be to rig 90 deg to the defect, kinda set it up like a fishing pole method. Or even have 2 rigging points and rigging lines, one higher above defect, one below?
 
Towards the defect would be my choice. That way you would load the tree on the opposite side. You will however still compress the fibres around the defect, which could cause failure.
If you are using a GRCS or Hobbs etc with the ability to tension & remove slack from the running line, I would do so, but never at the expense of not letting it run.
Great thread - got me thinking hard
 
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Thanks Pete that's the idea thinking hard;) I just know there are so many variables but is there no science in testing average amount of force to break trees? I found one file in my research from 1908 about it but it was more about dry lumbers.
It did averages on breaking in cross grain and vertical shear, even touched on structure loss of knots in wood.
Regardless I will be looking for more info to feed this thread.
 
A lot to think about.
Compressing wood is obviously stronger, bending less so.
Are you bending or compressing the best or worse part of the wood in the defect. A good way to look at it is if it is notch in compromised tree
 
Slight derail here, I'm somewhat unfamiliar in dealing with defects and today inspected a 15 metre poplar that appears to have an almost totally hollow trunk . I would say all the heart wood is either missing or rotten (there are 3 evenly spaced hollows up the entire trunk, I checked the lowest one and it reveals around 2 metres of hollow trunk). Luckily I have a tip in an adjacent taller poplar. I'm unfamiliar with poplars altogether but I know they are weak and snappy, if the entire tree were to fail it could take out a very thick powerline which is located within 2 metres of the hollow tree. Based on the description does this sound like a significantly hazardous tree where total failure is a realistic possibility?
 
A lot to think about.
Compressing wood is obviously stronger, bending less so.
Are you bending or compressing the best or worse part of the wood in the defect. A good way to look at it is if it is notch in compromised tree

I thought I heard that tension wood has twice the strength as compression wood, as in twice the force to tear it end from end, than buckle it/ crush it.
 
Couldn't find anything regarding specifically wood grown in tension vs wood grown in compression. But what I am trying to remember and visualize is the failures witnessed over the yrs. I think it's pretty safe to say compressed tension wood is stronger than tensioned compressed wood. May not be true statement for all species. If you compress compressed wood what happens? Tension tensioned wood?
Need to bend some wood at the apex of a dog's leg..
There's a picture on my website Kingtree.ca of a locust failure at a dog's leg. Check it out see what you think.
http://www.kingtree.ca/images/cracked-limb-large.jpg
 
I'd say I prefer by far tensioning tensioned wood than compressing it. A tinny wall of tensioned wood can sustain a huge load in tension but comparatively very few in compression, like a wire rope.
In opposite, it doesn't really matter for the compression wood, usually it's more a thick piece of wood to avoid bending and crunching, so there are plenty of fibers to hold, even if they aren't exactly designed for this task.

My choice could depend on the shape of the tree : You don't want to add strain to an already loaded side, like a leaning tree. Try to substract the forces instead of adding them.
It depends on the shape of the defect too, or if you prefer, the transversal shape of the holding wood. Put the load in the direction of the beefy dimension of good wood, like a beam to hold the floor.
But it isn't easy each time to tell before wrecking the tree.

There's a picture on my website Kingtree.ca of a locust failure at a dog's leg. Check it out see what you think.
Well... don't put your foot on it !:D
 
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