2-DIMENSIONAL MAGNETIC ALGORITHM TO DETECT REINFORCING STEEL

A two-dimensional algorithm has been developed to determine the locati ons and sizes of steel bars in reinforced concrete members. This algor ithm uses magnetostatic relationships to relate measured distortions i n 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 bet ween measured and computed distortions of the magnetic field. Finite-e lement analyses were conducted to simulate the interaction between ste el bars and an imposed magnetic field. On the basis of the simulated m agnetic distortion, the algorithm accurately identified the location a nd size of a single bar even when 20% error was induced in the magneti c distortions. The algorithm also identified two bars spaced horizonta lly or vertically, However, if one bar was much closer to the receiver s than the other, only the closest bar was identified accurately, When 10% error was induced in the simulated magnetic distortions, the algo rithm accurately located two bars only when the areas were already kno wn.