Tree Cabling| Bracing| Dynamic| Static

Eric Frei

Documents on how to brace and cable trees

Attached Files

	cabling and bracing.pdf (600.5 KB, 904 views)
	BRACE_RODS_FOR_CODOMINANT_STEMS_smiley.pdf (90.9 KB, 405 views)
	Cabling_Tree.pdf (178.5 KB, 573 views)
	Cobra_Literature.pdf (438.2 KB, 431 views)
	Cobra_Instruct.pdf (3.45 MB, 431 views)
	cobra_us_brochure.pdf (856.8 KB, 412 views)
	BracingISA.pdf (719.4 KB, 611 views)

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TrevMcRev

I'd like to know why in the first doc, fig 2 c, Hub & Spoke should only be used when no other method can be???

Some reasoning or justification from an engineering point of view would be nice.

Apart from the cable manufacturers recommending the other methods because they use heaps more product...

treeseer

Trev it may be that if there are an even # of trunks it is better to have separate cables because there is not a chance the hub will fail. re amt of mtl i don't see a big dif.

The UT pub just nutshells the bmp's. It is a bit dated but still generally accurate--the standards and bmp's and the harris book have been updated since. smiley's paper was key in getting higher bracing--good research effectively used.

TrevMcRev

Yeah with steel cable its probably not significant in materials cost, but with cobra it is.

I've used cobra on a central ring system (hub & spoke) with no real concern about ring failure, you can use rated crane lifting rings.


I forget the specs on this one, but several ton i think.

It's been in about 4 years now.

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treeseer

looks like an effective system, something the ANSI committee should review. no matter if you're in australia you can send it to them.

Eric Frei

Will get to logical answer at bottom.

Nope, missed the point. Competency Not Achieved.

Before you do anything the point is in C the stems can move in direction of arrow shown which cannot happen with D.

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treeseer

OK your reason may be better. I shall study harder, sensei.

Eric Frei

Just happened to be writing a report and cabling popped up, so I made this picture that can help others.

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Chris in Dallas

Does anyone have information regarding bolt capacity in trees? I'm a structural engineer (and arborist), and could run some calculations, based on NDS wood design, but I don't think they would accurately reflect real world capacities. Are there any published results based on pull tests on larger trees?

When does a higher grade threaded rod, for instance, make sense when bracing? Stocked galvanized rod is all A307 or A36 steel - yield strength of 36 ksi. Sherrill supply here in the states sells (currently - that may change considering my conversation with them) 3/4" lag threaded grade 8 rod, but it is not galvanized. The lag threads certainly aren't good at nut holding, and the lack of corrosion protection is something I can't accept for outdoor use.

Obviously pull tests would have to test for various failure modes, using various steel grades for rods, nuts and washers, and for different sizes and thicknesses of hardware. ANSI A300 just lists the number of rods of certain diameters that should be used with stems and crotches of different diameters. There is no mention of steel grade, or even galvanizing.

Is better info out there somewhere?