Mechanical behavior of trees with structural defects under lateral load: a numerical modeling approach

Abstract

Tree structural defects are a common cause of tree failure. These structural defects often result from progressive wood decay over time. Therefore, special attention is required to study the changes in the lateral responses of trees as defects are introduced. This can show how, using these changes, significant tree defects that can ultimately disrupt tree stability be detected. In this study, a three-dimensional (3D) numerical model was proposed to investigate the mechanical behavior of trees with structural defects under lateral load. The 3D numerical model was verified by non-destructive tree pulling tests with the incorporation of the overall stiffness of the tested trees. Then, trees with structural defects were simulated with different tree geometries and defect sizes. In addition, to examine the effect of decay volume extents and deterioration in elastic modulus due to decay, a simplified two-dimensional (2D) numerical simulation was performed. Through comparison with the results of the tree pulling tests, the 3D numerical model was found to be appropriate and applicable for the evaluation of the tree’s lateral response as well as the effects on tree stability. Numerical analysis results, therefore, confirmed the fact that the mechanical behavior of the tree under lateral load is strongly dependent on the presence of significant decay that can cause whole tree failure.