Influence Of Steel Ratio On The Acoustic Wave CT Inversion Accuracy Of Concrete Structure

Reinforced concrete structures are widely used in civil engineering applications. The results can be considered in the process of maintenance in order to take the necessary repair action, extend the service life of the structures for a long period of time and contribute therefore, to the safe and economic infrastructure management. It is increasingly strict to safe and normal operation especially in the important large reinforced concrete building structure, when emphasizing its policy of security, integrality and durability. The acoustic wave computer tomography(CT) technique is the main NDT methods of reinforced concrete structures. The steel reinforcement ratio influence of acoustic CT inversion accuracy could be used to reasonable design scheme of testing and the results of data analysis. To the following conclusions:(1) Through the finite element software ANSYS/LS-DANA middle holes and reinforced concrete structure finite element models are established, simulation of stress wave propagation in inhomogeneous medium concrete. The study shows that stress wave propagation velocity in reinforced concrete is obviously better than in concrete. The first wave amplitude change more, wave attenuation degree is larger, and the speed of different location to receive- time curve of the first arrival travel time is different; The fluctuations in the finite element method to simulate the wave propagation is feasible, and the more perfect image reconstruction of multiple sample data is provided.(2) The excitation frequency is in influence of on the acoustic wave CT inversion accuracy of concrete structure. Firstly, some models that contain defect and different amounts of transverse or longitudinal steel were built using Finite Element Analysis. Secondly, the propagation of elastic waves in the reinforced concrete structures was calculated and simulated. Finally, the objective of tomography was to provide visualization and compared of the result with the excitation frequency of 100 KHz and 200 KHz. The results demonstrate that different excitation frequency makes some difference in detection of defects in the different steel ratio interior of structures by CT. With the horizontal steel ratio being smaller, CT can locate the defect and display the obvious reinforcement in a structure for 200 KHz.With the horizontal steel ratio being bigger, CT can locate the defect in a structure for 50 KHz, and there was a little of pseudomorphism.(3) The test scheme and the horizontal and vertical steel are in influence of on the acoustic wave CT inversion accuracy of concrete structure. Some models that contain defect and different amounts of transverse or longitudinal steel were built using Finite Element Analysis, then calculating and simulating the finite models, in the end, the objective of tomography was to provide visualization and compared of the result of acoustic CT inversion. The results demonstrated some conclusions. Firstly, with the horizontal steel ratio being smaller, CT is more sensitive to the detection of defect and steel in concrete. But the influence of the vertical steel ratio on the acoustic wave CT inversion accuracy is relatively small, and it cannot clearly show the vertical reinforcement position in concrete. Secondly, The test plan of right receiving signals is better than the test plan of side and right receiving signals, because it shows the location of the hole defects in concrete clearly, and with the increase of reinforcement ratio, acoustic CT inversion accuracy is lower. Finally, with the increase of the amount of transducers, and increase of reinforcement ratio, concrete acoustic CT inversion accuracy is lower.Through the study of this paper, it can emerge the basis for reinforced concrete internal defects, also provide a valuable reference for the engineering application of the acoustic wave compute tomography.