Research On Monotonic Constitutive Model And Hysteresis Performance Of Q355 Steel With Different Thicknesses Under Chlorine Salt Corrosion Environment

With the development of construction industrialization in China,the low-alloy steel Q355 is widely used in the large-scale construction field as a mature and comprehensive material.For the steel structure that has been in the conditions of marine and saline soil for a long time in China,with the penetration and erosion of chloride salts,the condition of service has becoming increasingly harsh,and the problems of safety and durability have become increasingly prominent.At present,scholars at home and abroad have carried out some research on the corrosion performance of reinforced concrete structures and steel structures,but there are few studies on constitutive models of corroded Q355 steel with different thickness under monotonic loading.This paper carried out the experimental research,finite element method simulation and theoretical investigation on the corroded Q355 steel with different thickness.Through means of monotonic tensile test and low cyclic loading test on Q355 steel with different thickness,this paper reveals the relationship between corrosion degree of steel and mechanical performance indexes,and the constitutive model of corroded Q355 steel related to section loss rate under monotonic loading was established.The corrosion model was established by three-dimensional reverse reconstruction technology,and the finite element method(FEM)model of corroded steel was established by ABAQUS software,.The FEM results were compared with the test damage phenomenon and mechanical properties.The main work is as follows:(1)Through the artificial accelerated corrosion method,the accelerated corrosion test was conducted on Q355 steel with thickness of 6 mm(S1,LC1),12 mm(S2,LC2)and 18mm(S3,LC3)using 50 g/L sodium chloride solution.The corrosion degree of Q355 steel is characterized by mass loss rate and section loss rate.The relationship between mass loss rate and corrosion time is power function corrosion model,and the relationship between section loss rate and corrosion time is linear relationship.(2)The monotonic tensile test was carried out on corroded specimens with different thicknesses,and the degradation law of mechanical properties of corroded steels with different thicknesses and ages was studied,and the corresponding relationship between mechanical properties parameters and mass loss rate and section loss rate was established.The constitutive model based on the quadratic plastic flow model is established for S series corrosion specimens,and the corrosion constitutive relation related to the section loss rate is given.(3)The hysteresis performance of corroded specimens with different thickness was studied by low cycle loading test.The hysteresis performance,energy dissipation capacity and stiffness degradation of the corroded specimens with three thicknesses were compared and analyzed.(4)Three-dimensional reverse reconstruction technology and ABAQUS software are used to analyze the corroded S1-7 and S2-9 specimen.The correctness and feasibility of the FEM model are verified by comparing the numerical analysis results with the test failure phenomenon and monotonic tensile mechanical properties.