Recently, the steel cable used infrastructures are improved with progress in construction technology. In
particular, the steel cable in long span bridges such as cable stayed bridges and suspension bridges are critical members
which suspend dead load due to the main girders and bridge floor slabs. Damage at cable members can occur in the form of
cross-sectional loss caused by corrosion and fracture, and it can lead structural failure due to concentrated stress of the cable.
Therefore, nondestructive examination for steel cables is necessary so that the cross-sectional loss can be detected. This
study proposes a steel cable health monitoring technique using an elasto-magnetic (E/M) sensor installed in a cable climbing
robot. The E/M sensor is applied to detect the cross-sectional loss in this study while it was originally developed for
measuring the tensile force in the previous works. To verify the feasibility of the proposed damage detection technique, steel
bars which have 4-different diameters were fabricated and the output voltage value was measured at each diameter by the
E/M sensor. Optimal input voltage and working point are chosen so that the linearity and resolution of results can ensure
through repeated experiments, and then the E/M sensor scans the output voltage of the specimens based on the selected
optimal condition. This E/M sensor based monitoring technique will be incorporated into the cable climbing robot in the
further research. This proposed approach can be an effective automated tool for steel cable health monitoring.