Study On Impact Resistance Of Steel Pipe After Corrosion In Marine Environment

The steel pipe structure is the main structural form of the offshore platform.With the increase of the use time,the corrosion of the steel pipe in the splash zone is increasing,and the splash zone is also a part of the offshore platform that is threatened by the impact of external loads.When the members experience impact loading,the structural bearing capacity,stability,and force forms are all greatly weakened and changed.Under the action of impact loads,the entire structure collapse may occur.Therefore,the studies on impact resistance of corroded pipe structures have great engineering significance.This research aims to study the behavior of corroded steel pipe under lateral impact loading.The main aspects are listed as follows.(1)A marine environmental simulation equipment was designed and built,which can realize the automatic operation of tides,waves and temperatures.An electric accelerated corrosion test scheme in a simulated marine environment is designed.Six steel pipe specimens completed corrosion tests at different times,and a high-precision 3D scanner was used to measure the depth of the corroded steel pipe.The results show that the change trend of corrosion area morphology and corrosion rate are similar to natural corrosion,and the simulated corrosion test is relatively successful.(2)Experiment of corroded steel pipe was conducted through the drop hammer rig.Failure modes,time history of impact force cures,time history of deformation curves and time history of strain.The results show that the limited local corrosion has less influence on the overall damage morphology of the specimen,corrosion defects make the upper surface of steel pipe yield earlier and weaken the elastic recovery ability.By analyzing the strain history curve,it can be concluded that there is a serious stress concentration in the corrosion area.(3)Finite element(FE)simplified models for local corrosion and impact tests.The FE models results are compared with experimental results on time history of impact force curves,time history of deformation curves,and such comparison verifies the accuracy and reliability of the FE model.Through the output stress cloud diagram,the existence of stress concentration in the corrosion area was verified,and the force of the steel pipe is analyzed by outputting the internal force of the component.