Corrosion is one of the most important causes of deterioration of steel girder bridges which affects then-long term mechanical performance, usability and durability. Lack of information on yield and ultimate behavior of corroded tensile members make it a difficult task for the civil engineers to evaluate their remaining strength which eventually accounts for the estimation of useful service life, decisions on necessary retrofit or replacements to promote public safety. In the past, many experimental studies were done on corroded coupon specimens such as JIS No.5 with about 30mm width, in clarifying the influence of corrosion on the remaining strength. However in actual corrosion conditions, severe corrosion damages with large corrosion pits exceeding 30mm in diameter are observed in aged steel bridges. Therefore the existing coupon specimens would not reflect the actual effects of corrosion in their corresponding tensile tests. A more accurate method of remaining strength estimation for the corroded tensile plates based on the experimental results of tensile tests conducted on 26 specimens having different corrosion conditions and wide widths of 70-180 mm is presented in this paper. These results divulged the importance and possibility of using of a representative effective thickness parameter on estimating the residual yield and tensile strengths of corroded steel plates with more accuracy. Therefore, two approaches to estimate the remaining yield and tensile strength of corroded steel plates are proposed by considering the statistical parameters such as initial thickness, standard deviation of thickness etc., which represents the condition of corrosion surface. The proposed methods revealed more accurate and reliable estimation for the maintenance management of existing corroded steel structures.
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