Ultrasonic Analysis Of Working Stress Of Reinforced Concrete Under Load

The detection of the existing concrete structure is the premise to ensure the normal work.In many detection methods,ultrasonic nondestructive testing technology shows its unique advantages,the main functions are defect measurement,strength measurement,distance measurement,stress measurement,etc.,and the work stress is often the focus of the detection work.Before that,most engineers focused on the stress detection of plain concrete,but the application of plain concrete in the actual concrete structure has great limitations.Therefore,on the basis of linear wave theory and nonlinear wave theory,this paper establishes the relationship between ultrasonic parameters and working stress of reinforced concrete through the experiment of the influence of different factors on the correlation between ultrasonic parameters and working stress.The main contents and conclusions are as follows:(1)Based on the theory of aggregate grading,according to the test requirements,the aggregate is randomly generated by MATLAB and the process of placing is realized,and a two-dimensional meso concrete model is constructed.The acoustic field and stress field in ABAQUS finite element software are coupled by converting the elastic modulus and Poisson’s ratio to realize the propagation simulation of ultrasonic wave in the loaded concrete.According to the simulation analysis,three ultrasonic parameters,i.e.wave velocity,dominant frequency amplitude and nonlinear coefficient,are selected as the dependent variables of the subsequent tests.(2)In signal processing,FFT is used to analyze the frequency spectrum of sound wave.The number of sampling points,sampling frequency and the length of waveform interception are properly selected to improve the frequency resolution and make the converted signal more effective and accurate.(3)This paper discusses the influence of reinforcement position,specimen size and void size on ultrasonic parameters of reinforced concrete structure under the action of working stress.On the premise that there is no void in the specimen,the change relationship is established.The working stress stage method and function fitting method are used to evaluate the working stress of reinforced concrete.The feasibility of the evaluation method is verified,and the advantages and disadvantages of the two evaluation methods are compared.(4)According to the test results,under the condition of no stress of the test piece,the authenticity of the test data is verified by referring to the specification sl352-2006 for hydraulic concrete test.At the same time,considering the working stress state of the test piece,the wave velocity correction coefficient of the transverse reinforcement and the longitudinal reinforcement and the cavity size correction coefficient are supplemented...