頁籤選單縮合
題 名 | 應用複合振動法測定結構用製材品之彈性係數及剪斷係數=Measurement of Modulus of Elasticity and Shear Modulus of Structural Lumber Using Complex Vibration Method |
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作 者 | 卓志隆; | 書刊名 | 林產工業 |
卷 期 | 19:1 2000.03[民89.03] |
頁 次 | 頁37-48 |
分類號 | 474.3 |
關鍵詞 | 結構用製材品; 彎曲一扭轉複合振動; 動彈性係數; 剪斷係數; 振動模態; 細長比; 靜曲性質; Structural lumber; Complex vibration of bending and twisting; Dynamic modulus of elasticity; Shear modulus; Vibration mode; Slenderness ratio; Static bending strength; |
語 文 | 中文(Chinese) |
中文摘要 | 本研究以彎曲-扭轉複合振動法及縱向振動法測定24木結構施工法中經常使用之製材品彈性係數及剪斷係數。複合振動之訊號經加減運算及FFT分析可成功判定彎曲及扭轉振動模態的各共振頻率,由此可同時測定製材品的彎曲動彈性係數及剪斷係數,本研究並得到如下之結果:1.各製材品間之縱向、彎曲動彈性係數及剪斷係數,在5%顯著水準下具有差異性。2.各製材品之平均E/G值以基本共振頻率計算時為12.5,愈高次的振動模態其E/G值會變小。3.縱向及彎曲動彈性係數可有效預測製材品之靜曲強度。4.縱向動彈性係數及剪斷係數幾乎不受振動模態(1st~6th)及試材細長比(10~60)的影響。而彎曲動彈性係數則在較高次的振動模態及低細長比狀況時,其值會明顯降低。如採用Euler樑理論計算兩端自由狀態時之彎曲動彈性係數,且允許5%誤差,則試材之細長比應在20以上。 |
英文摘要 | The objectives of this study were to evaluate the modulus of elasticity and the shear modulus of structural lumber by complex and longitudinal vibration methods. Test structural lumber are frequently used in 2'×4' wood frame house construction. The isolation of the time domain signals of bending and twisting vibrations from the complex vibration was made by performing an addition to and a subtraction from the complex signals. The isolated signals were introduced to a fast Fouier transformation spectrum analysis, and the resonance frequencies of various vibration modes were identified. This proposed method enabled a simultaneous determination of flexural dynamic modulus of elasticity and shear modulus of structural lumber. Futhermore, the following conclusions were obtained from this study. 1. Difference in dynamic moduli of elasticity and shear moduli among various structural lunber were significant at the 5% level. 2. Averag E/G value of structural lumber; calculated from fundamental resonance frequency, was 12.5. E/G values would decrease at higher modes. 3. Static bending strength could be predicted well by longitudinal and flexural dynamic moduli of elasticity. 4. Whatever the orders of vibration modes (1st-6th) and slenderness ratios (10-60) of test specimens were, the calculated longitudinal dynamic moduli of elasticity and shear moduli were almost constant. But , flexural dynamic moduli of elasticity decreased obviously at higher vibration modes and lower slenderness ratios. If an error of 5% is allowed in the determination of the flexural dynamic modulus of elasticity according to Euler beam theory, then the slenderness ratio used should be 20 or above for a beam with free ends. |
本系統中英文摘要資訊取自各篇刊載內容。