The Steel Rebar Defect Detection By Using Ultrasonic Guided Waves

The steel rebar plays a very important role in civil engineering construction and often act as the structure that bear force.But these components usually bear a huge load and deformation in the structure, inevitably it will produce injury, but these injuries are very small and difficult to detect, In addition, civil engineering structures often in the open-air environment, steel corrosion is inevitable. And the steel corrosion can be find everywhere, steel corrosion lead to the decrease of cross-sectional area, the reduction in strength,even will cause severe structural collapse. Therefore, this paper analysis the signal of ultrasonic guided wave detection, make a reasonable evaluation of component damage, and guarantee the safety of the member. This paper mainly as follows:Firstly, numerical simulation for different defect length and depth of the steel by the ultrasonic guided wave. Establish the steel rebar defects model by ANSYS software, take five cycles Hanning window modulated sine wave as excitation signal, exporting the data using the post-processing module Transient Force. Research different damage conditions of steel rebar by using ultrasonic guided waves, also, the relationship among reflection and transmission coefficients and the degree of injury. Using wavelet time-frequency analysis method, obtained under different damage states ultrasonic guided wave propagation modes.Secondly, based on numerical simulation results, and test steel rebar defects by using ultrasonic guided waves test, got its wave signal. Method using the cut-off frequency of the filter detection signal processing, analysis of different degree of injury and the relationship between ultrasonic guided wave signal. Difference method location method based on reflection and transmission coefficients and the relationship between the degree of injury, damage to determine the location and degree of injury reinforcement. So as to prove the correct of the results in the simulation. Prove the validity and correctness of the steel rebar defect by using ultrasonic guided wave.Finally, contrary to the corrosion damage in steel rebar concrete, apply electrochemistry DC corrosion method accelerated corrosion test for the steel rebar concrete beam. And distinguish between different specimens by controlling the amount of corrosion. Using ultrasonic wave guide testing equipment to test, by comparing the signals that front and rear for the corrosion, the signal change in the condition of analysis for different corrosion, obtain the corresponding relationship between the signal and the corrosion extent. Three-point bending test for different corrosion beams, so can obtain the change of the bearing capacity with different corrosion condition.The above research show that the ultrasonic guided wave detection steel rebar defects are feasible, can be correctly analysis of the size, location and depth of defects, and can monitor the condition of reinforcement corrosion. This paper provided a solid foundation for future research of the detection of the steel defect.