Study On Mechanical Properties Of Parallel Steel Wire With Specific Corrosion Rate Under Alternating Stress

As the main load-bearing member of the cable type bridge,the slings are mainly composed of steel strands or high-strength parallel steel wires.A large number of engineering examples show that in the actual operation of the bridge,the sling will in a alternating cyclic load and corrosive medium environment for a long-term,so that the mechanical properties and bearing capacity of the sling are reduced.In some severe cases,it led to sling breakage.Therefore,it is of great significance to study the bearing capacity and residual fatigue life of rusting cable steel wire after alternating cyclic load,so as to ensure the safety of the cable in the service life of the bridge.In a suitable time to replace the cable to extend the service life of the bridge.The main research conclusions of this paper are as follows:(1)Combining with domestic and foreign literature,the research status of mechanical properties and residual fatigue life of rusted steel wires are summarized.The causes and types of rusting steel wire rust are systematically analyzed.The causes are mainly because of the aging of PE materials,load effect,different batches of raw materials and mechanical damage during construction.The types of corrosion mainly are uniform corrosion,pitting corrosion,stress corrosion,and corrosion fatigue.The analysis and evaluation methods of sling steel wire after corrosion are focused on tin this paper,too.(2)The sling wire is placed under alternating stress and corrosive environment,and the electrified accelerated rust test is carried out to observe the etch pit condition of the steel wire when the specific corrosion rate is 5%,7.5%,and 10%.The three-dimensional dimensions of the total and local corrosion pits of the steel wire in a specific corrosion rate are statistically analyzed.(3)The mechanical tensile of steel wires with different corrosion rates and different notch depths are tested,both of the effects of total and local corrosion rates on the mechanical properties of steel wires are analyzed.The relationship between the fracture morphology of steel wire corrosion rate and etch pit are analyzed.(4)Fatigue tests were carried out on steel wires with different rust rates and different nick depths,the fatigue life S-N curves at different rust grades were concluded.the effect of corrosion rate,rust length,etch pit number and depth on the residual fatigue life of steel wire and the corrosion rate of full rust and local rust steel wire with different corrosion rate were studied.Estimated the residual fatigue life of the initial defect or cracked steel wire by using the damage tolerance method.