風力負載下樹木穩定系統設計與分析

現今科技發展迅速人口也大量增長，這些發展也造成地球許多汙染與破壞，進而改變我們生活的現有環境，導致非季節性或超出歷史平均數值的天氣在莫名的時間與地點發生，這些不尋常的現象稱為極端氣候，其中的極端氣候熱帶氣旋在進幾年盛行且強度也明顯增大，在台灣最嚴重的災害莫過於颱風了，颱風造成的破壞非常巨大，而行道樹倒塌所產生的損失也不例外，若在颱風襲擊時有樹木穩定系統去穩固樹木就可以減少樹木倒塌的機率，大幅降低災害所造成的損失。本論文藉由靜態集成方法（Static Integrated Method）建立一套風力負載的理論模型去觀察樹木穩定系統中的影響參數，樹木的特徵條件選用台灣行道樹常見的尺寸，進一步調查所選用之樹種可承受的最大彎矩，並配合台灣夏季常見颱風的最大平均風速當作負載條件，利用空氣動力學中的數學模型來表示風力負載的強度搭配合理的假設與固定條件，匯入有限分析軟體去模擬現實中的情況，所呈現的結果再以物理現象去判斷分析是否合理。本研究的結果可瞭解到影響樹木支撐架破壞的重要參數與破壞的所在位置，讓設計者有一些基本的參數依據，可以在往後支撐架之設計中快速的切入重點，其中將設計二作為設計一的擴充版本，一方面可以增加使用者對於環境條件的因素去作選擇，另一方面在應力分析中也補足了設計一外在考慮條件的不足，兩設計比較可發現支架的系統化可以有效降低應力的集中與受力的情況，也發現到不只是支架的材料對其有影響，土壤與樁柱之間內部的互相作用也有很大的關係，最後也探討角度與支撐力的關係，隨著支撐角度越大所能承受的力也越大，但須考慮支撐環境是否允許。

關鍵字

樹木穩定系統；結構設計；風力負載； NASTRAN ；結構破壞性分析

並列摘要

The massive increase in population and the rapid development of science and technology have brought a lot of pollution and destruction to the earth, which lead to vary the environment we live on and produce unseasonal or unexpected weather. These unusual phenomena are called extreme weather. In recent years, extreme tropical cyclones have prevailed and their strength has increased significantly. The most serious disaster in Taiwan is the typhoon. The destruction of the typhoon is huge, leading to the collapse of street trees. If a suitable tree stabilization system is used to stabilize trees during a typhoon attack, the likelihood of the collapse of trees can be reduced, thus the damage caused by the disaster can be greatly reduced. In this paper, the SIM（Static Integrated Method）is used to establish the theoretical model of wind load, and the influence parameters of the tree stability system are observed. The characteristic conditions of the trees are selected from the common tree sizes in Taiwanese streets, and then we studies the maximum bending moment that this kind of tree species, with the maximum average wind speed of the typhoon in Taiwan as the load condition. By using mathematical models in aerodynamics to represent wind load strength with reasonable assumptions and fixed conditions and importing finite element analysis software for simulation, together with physical phenomena, we can determine whether the analysis results are reasonable or not. We study the important parameters that affect the destructed and damage location of the tree support system, so that the designer has some basic parameters, which can quickly go into the foci of the support system design. Design II as an extended version of Design I for one thing increases the user's choice of environmental conditions and besides another complements the Design I external considerations in stress analysis. Comparing the two designs, it can be found that the systematization of the bracket can effectively reduce the stress concentration and stress strength, and it is found that not only the material of the tree stabilization system affects it, but also the internal interactions between soils and piles. Finally, we can see that the force increases greatly when the support angle increases, but it must be considered whether the environment is allowed.