Study On High Cycle Fatigue Behavior Of T-shaped Circular Steel Pipe Joints Under Marine And Atmospheric Environment

The steel structure in the coastal area is prone to corrosion because of the high chlorine ion content in the air,and the structure is in the state of corrosion fatigue under the action of long-term wave load and wind load.At present,there is little research on the failure mechanism and mechanical properties of the corrosion fatigue coupling of the intersecting joints.Under this background,the corrosion fatigue behavior of T-shaped circular steel pipe joints under the sea-atmosphere environment is studied with reference to the marine and atmospheric environmental parameters of Lianyungang.The main work is as follows:(1)In this experiment,the accelerated corrosion test scheme under the marine and atmospheric environment is set,and the T-shaped circular steel pipe intersecting joint specimen is designed,and the accelerated corrosion test is carried out in three sampling periods,considering three kinds of corrosion degree;(2)The corrosion degradation constitutive model of the Q345 B steel is established on the basis of the mechanical tensile test of the sampling in the rust-based circular steel pipe,the static test is carried out on the axial force of the T-shaped circular steel pipe with different corrosion degrees through the axial force of the branch pipe,and the SCF value of the hot spot stress concentration coefficient of the cross node of the cross node is tested and analyzed,The influence of the hot spot stress of the T-shaped circular steel pipe with different degree of corrosion is obtained,and the result of the analysis is compared with the existing foreign norms;(3)Based on the high-cycle fatigue test of T-shaped circular steel pipe joints with different corrosion degrees,the crack distribution,stiffness degradation characteristics and fatigue life of the joints during fatigue are obtained.The high-cycle fatigue failure law of T-shaped circular steel pipe joints with different corrosion degree is revealed;(4)Based on the finite element analysis software ABAQUS and the fatigue analysis software FE-SAFE,the joint models of T-shaped circular steel joints with different corrosion degrees are established,which are identical to the physical tests,and the hot spot stress distribution and fatigue life of the intersecting joints are studied.The validity of the finite element analysis is verified by comparing with the physicalexperiment.The research work in this paper can provide reliable basis for evaluating the safety performance of in-service steel structures in marine environment,and has important practical significance.