ABSTRACT
This paper introduces the newly developed permanent magnet type Magnetic Main Flux Method (MMFM) system as a non-destructive inspection technology of bridge cables and post-tensioned external tendons in the field. The original MMFM system employs a solenoid type magnetizer to determine corrosion-induced section loss of the metallic components accurately. However, there are some difficulties in the field due to the heavy-weight of the magnetizer, external power requirement, on-site preparation time, etc. Therefore, a new but straightforward MMFM system was developed with permanent magnets to reduce the weight and improve the in-situ operation. For example, the weight of the permanent magnet type is much less than that of the solenoid type. Furthermore, the former doesn’t need the external power supply for magnetization and the number of operators is also reduced compared to the latter. As a result, the workability of the permanent magnet type is significantly improved. Even though two MMFM types produce different magnetic waveforms, they yield similar results to indicate comparable detection capabilities.
