부후 형상에 따른 노거수 구조 안정성 분석 = Structural Stability Analysis of Old-Giant Trees According to Decay Morphology

다국어 초록 (Multilingual Abstract)

Recent increases in the frequency and intensity of extreme weather events have resulted in a higher incidence of tree failure. However, structural stability assessments that explicitly account for decay, one of the primary causes of failure in old, large trees, remain inadequate. This study examined how variations in decay morphology and decay ratio affect tree structural behavior using Finite Element Analysis. Decay morphology was classified into six types: circular, elliptical, irregular, eccentric, single-opening, and multi-opening. The decay ratio was defined using established tree stability indicators, namely the t/R ratio, opening cavity ratio, and minimum residual wall thickness thresholds.
The principal findings are as follows. First, at a t/R ratio of 30%, differences in decay morphology and sound wood cross-sectional area exerted minimal influence on stress distribution, indicating structural stability. Second, at a t/R ratio of 10%, pronounced stress concentrations developed in regions with sharper decay geometry or thinner residual sound wood, leading to markedly reduced stability. Third, in trees with cavities, both the opening region and the opposite side displayed significant structural vulnerability. Instability increased substantially when the opening cavity ratio exceeded 30% for single openings and 40% for multiple openings. Fourth, even when the minimum residual wall thickness fell below the conventional threshold considered necessary for structural safety, the risk of failure remained low, suggesting that the traditional criterion may warrant re-evaluation for practical application.
This study quantitatively characterized tree structural behavior with respect to decay morphology and decay ratio, providing essential data to inform decision-making in tree stability assessment and conservation management.