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Access Type
Open Access
Document Type
thesis
Degree Program
Environmental Conservation
Degree Type
Master of Science (M.S.)
Year Degree Awarded
2013
Month Degree Awarded
September
Keywords
Damping, Oscillation, Trees, Dynamics, Co-Dominant
Abstract
Natural frequency and damping ratio were measured for ten forest grown northern red oak trees with co-dominant trunks. Steels support cables were installed in the canopies of five of the sample trees prior to measurement. Free vibration testing was performed during periods when leaves were and were not present. An accelerometer mounted at the base of the co-dominant union measured the acceleration time history during the free vibration testing. Natural frequency was determined from the acceleration time history using power spectral density analysis. Damping ratios were calculated from the power spectral density plots using the half power bandwidth method.
Trees with steel support cables had higher natural frequencies than trees without steel support cables. Sample trees had higher natural frequencies in the leaf off condition than the leaf on condition. The increase in natural frequency associated with the steel support cable was less pronounced in the leaf on condition. There was no difference between the damping ratios of cabled and non-cabled trees. Trees in the leaf on condition had significantly higher damping ratios than trees in the leaf off condition.
DOI
https://doi.org/10.7275/4517288
First Advisor
Brian C.P. Kane