For repair design and execution of corroded steel piles, it is important to know the corrosion tendency and their residual strength. The corrosion tendency of the 27 steel pipe piles obtained from the existing pier is observed by a supersonic thickness meter and a photomicro meter. From the measurement of the residual thickness of the steel pipe piles, the corrosion is concentrated on the steel pipe piles near the low water level and the uneveness of the surface is also large at this part.
　From the tensile strength test on the test pieces from the corroded steel pipe piles, the tensile strength of the steel is within the values specified at the Japanese Industrial Standard.
　The rigidity of the steel pipe piles can be estimated by the meanthickness of the steel according to the bending loading test. Further-more, the welding capacity of studs to the corroded steel pipe piles is examined by the tensile strength test and the bending test. When studs of diameter within twice of the corroded steel thickness are used, the breaking does not occur at the corroded steel but the studs.