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碩士論文公告區 |
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| 年度： | 91 | |
| 姓名： | 林政勳(Cheng-Hsun Lin) | |
| 論文題目(中)： | 細長混凝土桿之應力衝擊錘反應研究 | |
| 論文題目(英)： | Dynamic Responses of Slender Concrete Rods Due to Impact Hammers | |
| 摘要(中)： | ||
| 一般而言，基樁之現場非破壞檢測，通常無法隔絶上部結構之影響，所以檢測所得之反應訊號會有一定之複雜性。因此，當邊界條件或幾何形狀很複雜時，若能將基樁之軸向或側向反應訊號特性加以歸納，找出其中之規則性後，即可進一步了解其所具之邊界條件或幾何形狀所造成之影響。 於現場進行基樁檢測時，通常為了正確判斷基樁之幾何或邊界條件，和確保有足夠的反應訊號以供判讀，可選擇數種不同錘質之衝擊錘來產生不同之施力歷時。由於應力波的顯著波長與衝擊歷時有關，其對基樁之缺陷大小及型式的判讀，具有一定程度之影響。 本研究選擇三種簡單型式之桿件，配合七種不同之衝擊錘，進行數值模擬與試驗，探討不同衝擊錘對缺陷偵測之敏感程度為何。研究中先以數值模式一維線性桿件有限元素、二維軸對稱有限元素、ANSYS LS-DYNA SOLID 162及LS-DYNA SOLID 164，對完整桿件、含缺陷桿件、含弱層桿件之基本軸向及側向波動行為進行數值模擬，比較以上數值模式之可靠度，再與實驗相關波型對照之後，最後進行衝擊錘於不同桿件型式下之訊號基本特性歸納。 |
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| 摘要(英)： | ||
| In generally, when carrying out NDT field tests for piles, the influence of superstructures can not be effectively isolated, the signals obtained in the tests thus show certain complexity. Nevertheless, when boundary conditions or geometries are complicated, one would be able to recognize such spatial restraints on the test results, if one can induce the characteristics of the corresponding axial and lateral responses of piles and to summarize their generalizations. To obtain reliable test signals to correctly determine the boundary conditions or geometries of piles, one can usually use various kinds of hammer tips with different materials to produce different durations for the impact forces. Since the significant wavelengths of the stress waves are related to the durations of the impact forces, the selection of hammer tips would affect the assessment of the type and the size of defects. In this study, three slender concrete rods were erected and tested with seven different contacting tips of the impact hammer. To investigate the sensibility of impact durations to the detectibility of the defects, various numerical simulations and experiments were conducted. Four numerical models were used in this research; one-dimension line element, two-dimensional axialsymmetric element ,and ANSYS LS-DYNA SOLID 162 and ANSYS LS-DYNA SOLID 164 elements, to simulate the axial and lateral vibrations and wave propagations in an intact rod, a defective rod, and a rod with a weak layer. By comparing with results from numerical models and those of experiments, this study briefly generalizes the signal characteristics generated by various impact hammers on these three different rods. |
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| 檔案： | 沒有相關檔案 | |
| 相關連結： | http://ethesys.lib.cyut.edu.tw/ETD-db/ETD-search-c/view_etd?URN=etd-0825103-113513 | |