Study on stress measurement for steel bars inside RC beams based on self-magnetic flux leakage effect

Abstract

The self-magnetic flux leakage (SMFL) effect has been widely studied because it not only can identify early damage evaluation of ferromagnetic materials but is highly sensitive to the stress state. To promote the application of the SMFL effect in the health detection of reinforced concrete (RC) bridge, the whole process failure experiment of the RC beams under four-point bending loading was carried out and a method for detecting and quantitatively evaluating reinforcement stress in RC beams was established. A three-axis automatic displacement device based on metal magnetic memory was used to collect the magnetic signals of the RC beams under different loads, the magnetic signals under different values (LOVs) and multiple scanning paths were analyzed. Based on the magnetic signals under different stress states, a dimensionless parameter Aσ was defined to quantitatively calculate the steel bars stress of RC beams. The experimental results show that in the pure bending section of RC beam, the steel bars stress, and the dimensionless parameter Aσ emerged with a linear relationship. Furthermore, the effect of parameter lift-off values (LOV) on the test results was discussed.