Brudi's two talks are here
http://intern.tree-consult.org tcia tcia click on index.html
Prestress in Trees—Brudi
Gravity pushes pith down, force radiates outward.
Metal rings around barrels, curved skateboards, arches of concrete with steel rods inside are examples
Longitudinal prestress-- timber is weak in compression, strong in tension. Roots are hard to break because they have little lignin, but they are very tough.
Stems bend with wind=> tensile stress on one side, compressive on other sides
When slicing logs; the outside curves away in half moon shape, leaves middle straight
Origin in cell walls s1 S2 S3 lignins and polymers are incrusted in secondary wall. Cells shrink when older. Cracks form.
Young cells develop alone so they start out round, then narrow in response to pressure from contact with other cells.
Shows picture of hollow tree—“is it safe”? At 150’ no, 15’ high yes.
We must calculate load; lever arm, etc. Crown stiffness leads to higher wind resistance, shape/geometry is a big factor, live crown ratio, the 3-dimensional plant must be considered.
Material properties of the wood vary with the experience of the fibers—are they prestressed?
*Load-shape-material make the Triangle for engineers to consider before assessing risk*
Contrast this with assessments based on the 2-dimensional stem drilling for t/r; several questions from audience about this challenge to their reliance on stem formulae.
Aberdeen Scotland acer pseudoplatanus.
The crew cut a neighbor’s tree by mistake, the owner asked for 18000 pounds, got 500. Little old lady with kickass boots.
Measuring—sawing method with elastometer 1 with a 1/1000 accuracy
Beltlike forces; transverse stress in reponse to compressive force
Single hole method—drill in to release compressive stress, then transverse stress pushes 20 mm hole to 222 with ovalization
Green wood tests 10 tons
Tilia 2857 psi in sync with published, maple 2800 psi
Modulus of elasticity of green wood= stress/strain; “I don’t want to bother you with this stuff” 3 equations with cosines and pi and delta and iota
Same species exposed to more wind->30% stronger
Bavarian kings tree utterly hollow—is it safe? As shown in previous talks, it is, in his terms. Air thinness at altitude factored in, as is temp. They use 75 mph as load to test for, similar to our category 1 hurricane. figure roughness of terrain—other plants buffer. Calculated wind load transferred to base, safety 400% thick trunk resisted bending moment is cubed
Brazil hollow trees very high prestressing/speed of growth
Sia test method; crown shapes 1-4
Diameter it has/dia it needs = safety cushion
Prestress adds to safety—the difference is Reaction Wood!
Higher growth rate, higher prestress
Calculate strength loss—highest prestress in cambium
Gust reaction factors applied mathematically after test
Ansi standard for engineering—dynamic effects on structures.
Don Blair did a fine job with his Monticello talk—a very hollow tuliptree that had effectively compartmentalized so he noted there was “no question about its structural integrity”.
Robert Wells with Biodiversity and the Tree Care Industry
Son of a minister reads quote
T.S. Eliot “We shall not cease from exploration and at the end of all our exploring will be to arrive where we started and know the place for the first time.
Parents of man who died doing tree work big donors.
Bringing Nature Home how native plants sustain wildlife in our gardens douglas tallamy.
Wild creatures depend on our wildlife preserves to sustain them
**Johnson/Lyon books suited for labs not field!!!
Luley:
Clents ask is the tree healthy—how to quantify health? What is condition good or bad?
Communicate with each other. Document changes over time. Measurement metric?
*Stop mingling biological and structural mechanical health. Tree within a tree; apoplast within symplast
Nice eval report letterhead text left of pictures format white space
SPAD meter $1500 chlorophyll content/greenness quantified “You have to be smarter than the tool to use it”
Shoots elongation is the only tool to use when leaves are off—what about characteristics
Demonstrate to clients that tool will not penetrate soil
Great slides on rcx
“roots killed apparently by phytophthora”
Inonotus dryadeus knife stuck in root “totally rotted”???? no measurement
**??refers to drilling-backfilling as vertical mulching
1/3 structural
You gotta charge for taking risk, the rest of the work is time and materials.
Decay—General Assessment would identify most trees that fail.
Internal Defects need further assessment
Brudi Pulling test updates
Assessing the capacity of structures—service load, dead weight. Material strength and elasticity. Load-bearing capacity—even decaying wood has some** and oscillation.
Vta integrity structure decay attachments cracks defects, root strength, residual walls, wood properties
Windspeed must be factored—swirls around bldgs etc—pressure 2.25x on side.
Blast pipe effect when funneled,
and falls faster when going over bldgs
liontail increases oscillation
you don’t want holes in crown—edge effect
fine twigs key to damping
resonance frequency response
there is no even stress distribution but there is even strain distribution.
Elastometer strain gauge
Inclinometer 5/1000 of a degree
Sunken area in stem positive indicator of decay,from root or heart or…
Tilia in gray area between heaven and hell—did suffer from exposure
Lucombe oak with meripius clients wanted to keep but 7.3 tons of load.
Tree has big safety factor
Brudis advice—if you see changes then retest
Oak in aitrang bay in median planted 1848 high historical value
Root flare presence increases safety exponentially
Growth of tree and fungus coevolved
1642 tree moved autobahn 4 million euros old linden. Leaves browned—salt moving 30m. wrap in plastic? Walls?
Residual wall thickness 6 cm!!!!!!!!!!!!!!!!!!!!!!!!!!
Crown eccentricity
If a tree is prone to oscillation, dynamic effects must be incorporated
Strength of green wood varies little in temperate zone
Prestressing fibers increases safety margins
Diameter big factor—
Outer growth enhances safety exponentially
Very important for tree to outgrow its problems—equilibrium can be maintained between rot and growth
Diameter 2x is 8x more stable
t/r = 0.3 only reduces 25%
tipover resistance—400 trees observed close to same curve---.25 degrees is 40 % of tipping load
