- 學位論文
施工用塔式起重機之動態穩定性研究
The Dynamic Stability of Tower Cranes Working on Construction Sites
摘要
本研究主要探討建築施工用之塔式起重機，其斜張式吊臂在不同操作角度下，及不同的吊重下，所產生的動態特性及潛在之危險。研究過程中，先將塔式起重機系統模型簡化成一離散系統，以Lagrange方程式推導出該離散系統的運動方程式，再將運動方程式予以線性化，找出其可能產生內共振的條件，最後再以MATLAB SIMULINK 模擬該系統的動態響應，我們將討論系統在1:2內共振所引起的能量傳遞。一般地震的震動頻率大都是20 Hz以下的低頻震動。故當系統的自然頻率隨著 值增加而往低頻移動時，便增加了系統自然頻率落入地震震動頻寬內之風險性，此時如果系統系統結構又再耦合了內共振，將會大大增加起重機破壞的風險。在實驗驗證方面，本研究自行製作一塔式起重機模型，可調整不同的吊臂夾角，並且配合不同的吊重以調整出各種不同的質量比。由實驗之結果顯示，透過沒簡化過後的運動方程式所找出來的條件和實驗結果相差不遠，另一方面，當外激頻率 接近系統的第一個自然頻率時，能量會傳遞到高頻上，造成起重機系統的不穩定。
並列摘要
The main objective of the present study is to investigate the dynamic characteristics and potential risk of tower cranes which working on high buildings under various loadings and operation angles. A real tower crane system is modeled as a discrete one at the first step. Then, equations of motion for the crane system are derived by using the Lagrange’s method. The dynamic characteristics of the system is found at the conditions of possible internal resonance. MATLAB_SIMULINK is chosen as the tool for simulating the dynamic responses of the system. The energy transfer of the system in 1:2 internal resonance is noticed. If there is an internal resonance in the system while earthquakes, the tower crane may increase the probability of failure. Experiments are carried out after the completion of simulation. A scaled-down model is designed and manufactured to mimic the real tower crane. This model can be set with different operating angles. The results of the experiment show that the conditions, which are founded by the complete equations of motion, conform with those. Besides, when the excited frequency approaches the first nature frequency of system, the tower cranes system will be unstable because that the energy transfers to high frequency.