Model for calculating the corrosion degree of reinforcement based on self-magnetic flux leakage and genetic programming

Corrosion of reinforcement can significantly compromise the load-carrying capacity and durability of reinforced concrete (RC) structures. Accurate prediction of the corrosion degree of reinforcements is significant for the safe service of RC structures. This study considered the effects of concrete protective layer thickness and reinforcement diameter on the corrosion degree. First, 124 sets of experimental data were obtained through accelerated corrosion tests on RC. Second, the magnetic signal features that can characterise the corrosion degree were analysed and extracted using self-magnetic flux leakage. Lastly, the expression of the corrosion degree of reinforcement bars was constructed using genetic programming to incorporate the magnetic signal features and material information, and the significance and sensitivity analyses of these features were carried out. Results show that the coefficient of determination of the constructed expressions reached 0.97, and the average absolute error was 0.36%. The influence of reinforcement diameter and protective layer thickness on the corrosion degree is large and inversely proportional to the corrosion degree.