Structural mechanics study on the damage of tree stems caused by snow accumulating in the crown, 4: Application of the structural mechanics method to snow damaged stands
1989
Nakatani, H.(Toyama-ken. Forestry and Forest Products Research Center, Imizu (Japan)) | Kato, A. | Aiura, H.
In this report we examined the difference of resistance performance of tree stems between damaged and remaining trees in snow damaged stands, in order to confirm the application of the structural mechanics method to the damage of tree stems caused by snow accumulating in the crowns. We measured shape of the trunk, Young's modulus and the constant 'mu' for root system for all trees in snow damaged Bokasugi (Cryptomeria japonica D. Don) stands (25-year-old). The results are summarized as follows: The damaged trees had no significant difference to remaining trees for diameter at breast height, height of trees and the ratio of taper of stem. But the stem-form coefficient of damaged trees was higher than that of remaining trees. The snow load estimated from crown leaf weight by use of Matsuda's equation averaged 617kg, and had no difference between damaged and remaining trees. Provided that stems have the same mechanical properties, the averaged buckling load of stem of remaining trees and damaged trees are 747kg and 571kg respectively. The ratio of snow load to buckling load of damaged trees was larger than that of remaining trees. That is to say, the data of structural mechanics showed that damaged trees had small resistance against snow damage. This result indicates that structural mechanics approach is very effective to find the way of reducing the snow damage.
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