Two-Dimensional Magnetic Algorithm to Detect Reinforcing Steel

Abstract

A two-dimensional algorithm has been developed to determine the locations and sizes of steel bars in reinforced concrete members. This algorithm uses magnetostatic relationships to relate measured distortions in the magnetic field outside of a concrete member to the distribution of steel within the member. An optimal solution for the locations and sizes of the steel bars is determined by minimizing the difference between measured and computed distortions of the magnetic field. Finite-element analyses were conducted to simulate the interaction between steel bars and an imposed magnetic field. On the basis of the simulated magnetic distortion, the algorithm accurately identified the location and size of a single bar even when 20% error was induced in the magnetic distortions. The algorithm also identified two bars spaced horizontally or vertically. However, if one bar was much closer to the receivers than the other, only the closest bar was identified accurately. When 10% error was induced in the simulated magnetic distortions, the algorithm accurately located two bars only when the areas were already known.