Yoshimasa OTANI

Study of rust evaluation objectively quantification in Weathering Steel Bridges

Eiji IWASAKI and Masatsugu NAGAI


Recently, the reduction of maintenance cost (including life cycle cost) together with using in long term have been required. Because superior protected rust of coherency is formed on the surface, Weathering Steel Bridge can be used even with no painting. However, superior protected rust is easily got influence by environmental factors, so check and investigation are necessary in maintenance. There is a method of check and investigation named rust appearance evaluation. This method is used to evaluate state of rust by viewing so there is the problem of many different results depending on different evaluators.

By investigating Weathering Steel Bridge in Niigata, this study quantified the evaluation factor of rust appearance evaluation. Using the neural network with that data, this research is to investigate objectively the rust appearance evaluation and to distribute to maintenance problem in future.

The result of obtaining is described as follows.
1jThe appearance evaluation level 1 and 2 can not estimate if the input parameter is defined by only colorimetric investigation. In addition, this study was able to confirm that appearance evaluation level could not be applied to estimate quantity of rust thickness.
2jIt was able to confirm that high precision could be achieved with estimating an input parameter of adhesive tape examination.
3jIn case of fixed balance of appearance evaluation level, the precision is different by the number of learning data of each part.
4jThe future research is aimed to inspect the reason why precision is different by the number of learning data of each part. Besides, in other cases than M1- bridge, it is necessary to confirm whether it can be estimated or not.