Impact Performance Study Of Corrosive Steel Strands In Marine Environments

Steel strands are widely used in complex environments such as bridges and slope protection projects due to their high load carrying capacity and corrosion resistance.In recent years,with the construction of cross-sea bridges and other projects,the steel strand in long-term service in the marine environment is often subject to sulphate,chloride ions and other corrosive effects caused by rust,corrosion pits and other damage.In the earthquake,vehicles,ships and other impact instantaneous huge impact under the short time steel strand bearing load increased sharply,and plastic deformation or even be pulled off and failure,resulting in a significant reduction in structural load-bearing capacity,there is a greater safety risks.Therefore,the study of the corrosion impact performance of strands containing corrosion pits in the marine environment is of great importance to the safety of marine structural projects such as bridges across the sea.In this paper,the main ions and environmental conditions affecting the corrosion of strand in the marine environment are combined to simulate the test conditions of the real marine environment and the specimens of strand containing corrosion pits,and the salt spray corrosion comparison test and impact test of strand without and with corrosion pits in different corrosion cycles are carried out.The load-displacement curve and ultimate load carrying capacity were obtained,and the equation of corrosion damage rate and ultimate load was established.Finally,the finite element simulation software LS-DYNA was used to establish a finite element analysis model for the strand under impact loading,and a numerical simulation study was carried out to analyse the corrosion damage fracture characteristics,stress-strain variation law and ultimate load carrying capacity,and to compare and analyse the results with the test results.The following main results were obtained:(1)with the corrosion cycle gradually increased,the corrosion material colour gradually from white to dark brown,corrosion pit depth and area gradually increased and contains corrosion pit steel strand in the corrosion pit at the degree of corrosion more serious,showing uneven corrosion characteristics;strand quality loss,quality loss rate and cross-sectional loss in corrosion 0-8d when the quality loss degree is larger,8d after the quality loss rate gradually slowed down,containing corrosion pit steel strand quality Loss rate compared with the noncorroded strand containing pits increased by 10%.(2)The fracture characteristics of the strand under impact: the outer wire fracture for splitting,splitting-milling cutter type and slip separation type and other three forms,the central wire fracture for necking-milling cutter type;corrosion pits with and without corrosion pits steel strand ultimate bearing capacity with corrosion cycle are gradually decreasing trend,and the two different corrosion pits steel strand 0d and 56 d average bearing capacity decreased by3.28% and 4.37% respectively;its The nominal yield strength decreases with the increase of corrosion cycle,while the corrosion cycle has less effect on the nominal modulus of elasticity;when the corrosion cycle is the same,the nominal yield strength and modulus of elasticity of the strand with corrosion pits are smaller than that of the strand without corrosion pits;the ultimate load and corrosion damage rate are generally linear,and the fitted curve formula is obtained.(3)The fracture form and fracture process of the finite element model of the strand without corrosion pits and the strand with corrosion pits under different corrosion cycles are basically consistent with the test results;with the increase of corrosion cycles,the cross-sectional area of the strand gradually decreases,the bearing capacity of the strand gradually decreases and the plastic deformation capacity gradually becomes larger;the error between the average ultimate bearing capacity test value and the simulated value is within 5%,which means that the finite element simulation The analysis results are in good agreement with the test results.