ABSTRACT
In recent years, a large number of fatigue damages in steel bridge have been successively reported in Japan and this number, with the aging of the infrastructure, still shows tendencies to increase continuously. To maintain the large stock of bridges operating under good conditions and provide the required road services, management and maintenance of the existing infrastructures are indispensable.
Most of the existing bridge management systems and maintenance procedures rely on field data obtained through routine inspections and a large majority of bridge inspections are based on visual evaluation. However, not often are cracks in steel and welded connection elements obvious. The current inspection method requires that magnetic particle tests to be executed to all potential fatigue cracks areas found during visual inspections, so that appropriate measures compatible to the crack conditions can be provided.
Cracks in the paint membrane are considered to be one of the symptoms of fatigue cracks, which are usually hidden underneath the coating, and locations presenting coating cracks are considered to be potential crack locations. Thus, according to the current inspection requirements, all coating cracks found during visual inspections are to be submitted to magnetic particle tests, as presented in Figure 1. However, the magnetic particle test is a labor-and time-consuming method, as it requires the removal of the coating and proper surface treatment before the execution of the test and repainting after finishing the test. Proposed method for fatigue crack inspection. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig114_1.tif"/>
The present paper proposes the introduction of eddy current test, in the early stages of fatigue crack inspections as a screening method to reduce the number of potential cracks to be submitted to magnetic particle tests, as shown in Figure 1(Ichinose et al. 2014). Thus, by previously selecting the locations with potential cracks, the total time required for crack inspections can be reduced considerably.
Eddy current tests proved to be effective in detecting cracks, even in small tight areas. The introduction of eddy current test as a screening method prior to magnetic particle test made it possible to reduce the time required for crack inspections and also the total costs of inspection works.
