超音波法檢測鋼筋混凝土結構之鋼筋強度

Measurement on the Strength of Steel in Reinforced Concrete Structure Using the Ultrasonic Pulse-wave Method

鄭民鴻(Min-Hung Cheng)

指導教授 ： 吳志興

國立屏東科技大學/工學院/土木工程系所/碩士(2008年)

https://doi.org/10.6346/NPUST.2008.00049

摘要

本研究先建立鋼筋抗拉強度與鋼筋對打波速之迴歸方程式，再用改良式超音波法量測鋼筋混凝土試體之鋼筋波速CS，並將量測CS值代入迴歸式得到預測fy值。量測完畢後，將各試體敲開，取出鋼筋作波速對打量測及抗拉強度試驗，並與表面量測之CS值及預測fy值作比較，以評估預測值之準確性。
試驗結果顯示，最佳迴歸式為二次多項式fy=-0.03056966CS2+ 314.0110CS-801737，相關係數r2=0.959，其CS值之適用範圍介於4900~5200 m/s之間。而量測CS值之標準差僅於4.3~17.4 m/sec之間，變異係數僅在0.87×10-3~3.42×10-3之間。量測CS值與對打CS值之誤差百分比僅在-0.08%~0.65%之間，預測fy值與抗拉強度fy值之誤差百分比在8%以內，試驗結果顯示本法之準確性。

關鍵字

超音波 ； 非破壞檢測 ； 鋼筋抗拉強度 ； 縱波

並列摘要

The study first established a regression equation of the steel tensile strength and its wave velocity measured by opposite faces. The improved ultrasonic pulse-wave method was then employed to perform surface measurement on reinforced concrete specimens to measure the steel wave velocities CS. The measured values were substituted into the regression equation to obtain the predicted fy values. After the measurement, the specimens were broken. The steel bars were taken out to be measured the wave velocities by opposite faces and to be performed the tensile strength test. The values were then compared with the measured CS by surface measurement and the predicted value fy to evaluate the accuracies of the predicted values.
The test results shows that, the best correlation regression equation is a 2nd order polynomial equation fy=-0.03056966CS2 +314.0110CS-801737. Its correlation coefficient r2=0.959. The applicable range of CS value is in 4900~5200 m/sec. The standard deviations of the measured CS values are only in a range of 4.3~17.4 m/sec. The coefficients of variation are only in 0.87×10-3~3.42×10-3. The error percentages between the measured CS values
and those measured by opposite faces are only in -0.08%~0.65%. The error percentages between the predicted fy values and the tensile strength fy values are less 8%. The results shows the accuracy of the presented method.

並列關鍵字

Ultrasonic Pulse-Wave ； Nondestructive Test ； Steel Tensile Strength ； Longitudinal Wave

參考文獻

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