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Structural Features Related to Tree Crotch Strength

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dc.contributor.authorFarrell, Robert Williamen
dc.contributor.committeechairZedaker, Shepard M.en
dc.contributor.committeememberSmith, David Williamen
dc.contributor.committeememberLoferski, Joseph R.en
dc.contributor.committeememberKane, Brian P.en
dc.contributor.departmentForestryen
dc.date.accessioned2014-03-14T20:36:25Zen
dc.date.adate2003-06-11en
dc.date.available2014-03-14T20:36:25Zen
dc.date.issued2003-03-25en
dc.date.rdate2003-06-11en
dc.date.sdate2003-05-12en
dc.description.abstractCrotches were cut out of red maple (Acer rubrum), callery pear (Pyrus calleryana), and sawtooth oak (Quercus acutissima) trees (2.5â -7â d.b.h.) and then pulled apart in an engineering testing machine to identify physical parameters correlated with crotch strength. Parameters measured included the diameter of the branch and of the trunk above and below the crotch, angle of the branch and branch bark ridge, and the length of the crotch and the branch bark ridge. The force required to break each sample was used to calculate breaking strength based on the formula for bending stress. Each parameter was tested for correlation with crotch strength within the individual species and for the three species combined. The ratio of branch diameter over crotch width had the highest correlation coefficient for crotch strength. Branch angle was also correlated with crotch strength but not as highly as the ratio of the diameters. V-shaped crotches (those with included bark) were significantly weaker than U-shaped crotches for all species. The ratio of the two stem diameters greatly influenced the manner in which the crotches broke. In crotches where the branch diameter was 2/3 the size of the trunk or smaller, the crotch broke by being pulled directly out of the trunk. Crotches with branches more than 2/3 the diameter of the trunk broke when the trunk split longitudinally and had significantly lower strength values. These results indicate that increased crotch strength results from a small branch diameter relative to that of the trunk.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-05122003-124617en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-05122003-124617/en
dc.identifier.urihttp://hdl.handle.net/10919/32619en
dc.publisherVirginia Techen
dc.relation.haspartFarrellthesis0610.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectincluded barken
dc.subjecttree failureen
dc.subjectbranch failureen
dc.subjectcrotch strengthen
dc.subjectpruningen
dc.titleStructural Features Related to Tree Crotch Strengthen
dc.typeThesisen
thesis.degree.disciplineForestryen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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