Analysis of the probability of failure for open-grown trees during wind storms
Abstract
Although trees convey important environmental, economic, and sociological benefits on humans and
society, they can also cause significant economic and societal disruptions, especially when subjected to
wind storms in urban environments. Tools for proper assessment of the risk of these disruptions can be
of significant benefit to society. In this research an approach to quantifying the failure probability for
trees subject to wind storms is presented and illustrated by application to two specific maple trees in
Massachusetts, USA. The approach entails four specific steps: (1) Random wind time history samples
were generated using a modified Ochi–Shin spectrum, (2) these wind time histories were used as
loading time histories on finite element models of the example trees in both summer (in-leaf) and
winter (leafless), (3) maximum bending moments generated by the random wind time histories were
compared to the failure (yield) moment of the tree at 1.4 m above ground, (4) the failure/fragility curves
of the trees were estimated by Monte Carlo simulation for a range of average wind speeds and for 1000
independent wind time histories at each wind speed.
