Novel Method for Measurement of Rebar State of Cement Tower

Reinforced concrete (RC) structures are applied widely in low-voltage transmission towers. However, the structural damage caused by the corrosion or fracture of rebar in cement towers seriously affects the safety of transmission lines. Thus, the accurate detection of rebar can effectively maintain cement towers. There are many methods for detecting rebar corrosion, but most of them cannot accurately locate the corrosion, and they do not consider the factors such as the depth of the rebar and the different types of rebar. Therefore, this article proposes a rebar corrosion detection method based on the change of peak slope of magnetic flux density. First, this article analyzes the common pitting corrosion in engineering, then theoretically analyzes the principle of magnetic induction detection of rebar. Then the magnetic flux density peak and the measured position on the 2-D coordinate are plotted, and the rebar corrosion is detected according to the slope. The peak function of flux density without corrosion is fit by the least squares method and the corrosion criterion is defined. Finally, the proposed method is verified through simulation and experiment.