Experimental investigation of corroded CHS tubes in the artificial marine environment subjected to impact loading

Tubular structure is the main structure form of offshore platform. With the increase of service life, the corrosion of steel tube in the platform, especially in the spray splash area, is increasing day by day. At the same time, the spray splash area is also the part of offshore platform which is threatened by the impact of external loads. In this paper, the behavior of corroded circular hollow section (CHS) tubes under impact loading was studied. (1) A kind of test instrument to simulate marine environment was developed, which realizes the automatic operation of tide, wave and temperature. The scheme of electric accelerated corrosion test in artificial marine environment was designed. The corrosion tests of six CHS tubes at different times were carried out, and the corrosion depths of CHS tubes were measured by high-precision 3D scanner. The results show that the varying trend of corrosion area morphology and corrosion rate is similar to that of natural corrosion, and the artificial corrosion test has achieved good results. (2) The impact tests of corroded CHS tubes were carried out. The failure modes, impact force versus time history curves, displacement versus time history curves and strain versus time history curves of all specimens were obtained. The results show that the limited local corrosion has little effect on the overall failure modes of test specimens. The corrosion defects resulted in the pre-yielding of upper surface of CHS tubes and weakened the elastic recovery ability. The serious stress concentration phenomenon in the corrosion area can be inferred from the analysis of the strain versus time history curves. •An instrument was developed to realize automatic operation of tide, wave and temperature.•High-precision 3D data scanning was used to measure the corrosion depth of steel tubes.•There is a good correlation between accelerated corrosion and natural corrosion time.•Impact force, displacement and strain versus time history curves were all obtained.•The pre-yielding of upper surface of CHS tubes weakened the elastic recovery ability.