Study On Interface Monitoring Of Reinforced Concrete Based On Ultrasonic Guided Wave

In contemporary society,reinforced concrete structure has been widely used as the most important architectural structure by virtue of its advantages of simple materials and low price.However,with the increase of service time,the interface problems of reinforced concrete structures are prominent,which are usually manifested as local corrosion of reinforcement and debonding of reinforced concrete.Once interface problems occur,the bearing capacity of the structure will change,and even collapse will occur in serious cases.Therefore,in order to find problems in time,evaluate problems and give safety warnings to structures,ultrasonic guided wave monitoring technology plays an important role in this respect.Ultrasonic guided wave monitoring technology,as a real-time,online,dynamic and continuous non-destructive monitoring technology,combined with the finite element analysis software ANSYS,can carry out effective quantitative analysis on the interface problems of reinforced concrete.The specific research contents are as follows:1.Aiming at the problem of local corrosion of steel bar,the steel bar model without corrosion defects and the steel bar model with different corrosion defects were established.The five-period sine function modulated by Hanning window was input as the excitation signal of piezoelectric ceramic plate,and the transient analysis method in the finite element software ANSYS was used to solve the problem.The finite element software ANSYS was used to simulate the local corrosion defects of steel bar in different circumferential depths,different radial lengths and different positions.The relationship between ultrasonic guided wave signal peak value,reflection coefficient and damage degree under different damage states was studied,and the curve fitting of reflection coefficient and damage degree was carried out.At the same Time,the position of the defect was calculated based on the pulse echo principle and Time of Flight(TOF)method,and the position of the defect was determined by comparing the value of the second reflected echo peak.2.Based on the results of numerical simulation,the test platform was established.The self-made piezoelectric ceramic sensor was used in the experiment and the input excitation signals were consistent with those used in simulation.The ultrasonic guided wave signals under different damage states were collected.The finite impulse response(FIR)digital filter was used to filter the signal,and the relationship between the different damage degree and the reflection coefficient and the peak value of ultrasonic guided wave signal was obtained.Meanwhile,the pulse echo principle,Time of flight(TOF)method and comparison of the second reflection echo peak were used to locate the defect location.In addition,the finite element simulation and the test were compared and analyzed respectively from the time domain diagram and the results under different damage states.The experimental results were consistent with the results of the finite element simulation,which verified the effectiveness and accuracy of ultrasonic guided wave monitoring interface damage.The degree of reinforcement damage can be obtained by fitting the curve,which lays a theoretical foundation for the quantitative analysis of reinforcement damage in the future.3.Aiming at the debonding damage of reinforced concrete interface,a test platform was built directly,and ultrasonic guided wave was used to monitor the damage.The relationship between ultrasonic guided wave signal parameters and debonding degree is analyzed from time domain diagram,frequency domain diagram and energy attenuation respectively.The above studies show that ultrasonic guided wave can effectively monitor the interface problems of reinforced concrete,and can effectively analyze the size,depth and location of corrosion for local corrosion of reinforcement.In view of the debonding problem of reinforced concrete,the debonding degree can be effectively monitored.This study lays a good application foundation for ultrasonic guided wave monitoring interface problem.