Steel tubular members of offshore frame structures can suffer from corrosion damages in marine environments. Paint coating is usually applied for tubular members in splash and tidal zones as a corrosion protection. A typical mode of corrosion experienced in those members is distributed pitting corrosions as a result of degradation of coating materials. On the other hand, tubular members in water and soil zones are generally protected by a cathodic protection without coating materials, and a general corrosion spreading all over the surface is a typical mode of corrosion. In order to evaluate the structural integrity and resulting failure risk of offshore frame structures with corrosion damages, it is important to investigate the residual strength of corroded steel tubular members. In the present study, compressive and bending strengths of steel tubular members with general or putting corrosion are examined. Surface roughness measurements are made for tubular members with general corrosions taken from the splash zone, and ultimate strengths under axial compression and pure bending are examined both experimentally and numerically. Pitting corrosions as a result of degradation of coating are modeled based on the existing related test results and ultimate strength is examined numerically. Based on the obtained results, the applicability of existing design formula for the evaluation of residual strength of corroded steel tubular members is examined.
