Judging method of incompactness defect in node of concrete structure by detection by ultrasonic method

Abstract

The invention relates to a judging method of an incompactness defect in a node of a concrete structure by detection by an ultrasonic method. On the basis of the traditional method for detecting the concrete defect by the ultrasonic method, besides an acoustic velocity and a head wave amplitude, two variable acoustic parameters, namely a complex frequency difference and a cross-correlation coefficient, are added; each acoustic parameter is processed into an acoustic parameter judging factor and each acoustic parameter judging factor is processed into a normalized comprehensive acoustic parameter judging factor; a position detecting chromatogram is drawn out according to the comprehensive acoustic parameter judging factor; and the position and range of a suspicious defect are determined according to a red area in the chromatogram. By the method, the compactness quality distribution of concrete can be directly and accurately described; errors and judgment loss caused by adoption of a single acoustic parameter for judgment can be avoided or reduced; and the difficulty in final judgment when the judgment result of the single acoustic parameter is inconsistent is also avoided. The judging method can be widely applied to the judgment of the incompactness defect in the node of the concrete structure or other complex structures.

Description

technical field [0001] The invention relates to a method for judging the internal uncompactness defects of joints of concrete structures by an ultrasonic method. Background technique [0002] The internal defects of concrete structures refer to the uncompacted areas, voids, cracks or inclusions of sand and sundries that destroy the continuity and integrity of concrete and reduce the strength and durability of concrete to a certain extent; uncompacted defects It refers to the honeycomb shape formed by concrete leakage, segregation or suspension, or the loose shape formed by lack of cement, or the loose area caused by accidental damage. The existence of concrete defects will affect the bearing capacity and durability of the structure to varying degrees. The non-destructive testing technology for concrete defects can effectively find out the nature, scope and size of defects by using non-destructive methods for structural entities, so as to carry out repairing technical treatm...

AI Technical Summary

Problems solved by technology

When the quality of the tested structure is generally poor, the average value of the test data ( ) is low, and the large dispersion of data causes the standard deviation ( ) is too large, and the judgment value of the outlier calculated from this ( ) will be too small, that is, the standard for judging defects is lowered, which may lead to missed judgments and increase the risk of the user; on the contrary, when the general quality of the tested structure is generally good, the average value of the test data ( ) is high and the data dispersion is small, resulting in standard deviation ( ) is too small, the judgment value of the calculated abnormal value ( ) will be too large, and the improvement of the defect judgment standard may lead to misjudgment and increase the risk of the manufacturer

[0020] 3. The probability method is applicable to a variety of measured acoustic parameters, such as sound velocity, amplitude, dominant frequency, etc., but the results calculated and judged by various acoustic parameters are likely to be inconsistent or even contradictory. How to make a final judgment? The "Deficiency Test Procedure" requires the combination of the distribution of abnormal measuring points and the waveform status to determine, that is to say, testers need to make judgments based on experience and on-site conditions, and the increase in the requirements for the tester's experience level will inevitably increase the risk of misjudgment

[0021] 4. The sound parameters mainly used in the practical application of the probability method are sound velocity and amplitude, that is, the test is the travel time and amplitude of the first wave, and generally no or little information about the follow-up wave is used. Practical experience shows that whether the waveform is distorted is of great importance Judging the existence of defects is of considerable significance. The "Deficiency Testing Regulations" requires the judgment to be combined with the waveform status. However, because there is no quantitative description method for waveform distortion, many testers ignore this important source of information, which affects the judgment. accuracy

[0022] 5. The probability method is only used to find and define defects, and does not describe the overall mass distribution of the tested components

Third, the influence of the boundary effect of the complex shape of the structure and the interference of dense steel bars in the joint area lead to a large dispersion of the acoustic signal, which leads to the low value of the defect judgment when the probability method is used to judge the defect, and the phenomenon of missed judgment often occurs. Examples show that in concrete beams The preset obvious defects in the solid model of the column joints are not clear by the probability method

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