MasahiroJOMAE
Study on the Quantitative Evaluation Method of Corrosion Appearance of the Existing Weather-Resistant Steel Bridge
Eiji IWASAKI
In recent years, with the expectation to reduce maintenance costs through repainting, the application of weathering steels to bridges is increasing¡¤due to the formation of protective rust, weathering steel can be used in unpainted conditions. However, since the formation of protective rust can easily be affected by the environment, an accurate evaluation method for monitoring and diagnosing rust state of existing bridges is needed. In the past studies, we understood that there was correlation between the results of the scotch tape tests and the appearance evaluation. However, there is a limit in the appearance evaluation method which becomes more correct if it is evaluated quantitatively. Rust particles adhering to the cellophane tape , the existing weather resistance bridges some extent and progress of corrosion , also present portion of the state in which the plurality of particles overlap . In the history of image processing approaches to this state , it can not be objective evaluation .
In this study, apply the Watershed method, which is a valid image processing technique to split processing of particles was carried out a comparative study with the history of the technique with respect to quantification of the corrosion state of weathering steel bridge using the obtained feature amount . The results obtained are described as follows.
As a result, excess splitting by performing Watershed method for binarizing the cellophane tape test image occurs . Therefore , it performs a filtering process as a pretreatment , by smoothing the image , it was possible to solve the excess division of rust particles . Against rust particle image , it was confirmed that to obtain a high contribution ratio between the parameter and the rust thickness Metropolitan representing the rust particle shape than the history of the technique by applying the Watershed method .
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