Experimental Research On Mechanical Properties Of Naturally Corroded Cable

With the development of society and economy,the number of cable-stayed bridges in the world is rapidly increasing due to its advantages of large spanning capacity,low material consumption,simple construction and beautiful appearance.As the most important load-bearing member of the cable-stayed bridge,the cable-stayed cable is called the "life cable" of the cable-stayed bridge.Due to the long-term alternating load and exposure to the complex external environment,the stay cable is extremely susceptible to erosion and damage by the rusting medium,and the steel wire corrosion in the rope occurs.Corrosion not only causes the mechanical properties of the steel wire in the stay cable to deteriorate,resulting in a serious decrease in the average life of the stay cable.At present,domestic and foreign scholars' conclusions on the degradation of mechanical properties of corroded cable wires are mostly obtained by rapid corrosion experiments,which is controversial compared with the degradation laws of mechanical properties of naturally corroded cable wires.Therefore,in this paper,the static tensile test and fatigue loading test are used to study the degradation of the mechanical properties of the old bridge's rusted cable stays.The specific contents are as follows:(1)The local corrosion characteristics of the cable stays removed from the old bridge are analyzed,and the distribution of the corrosion of the steel wire in the cable in the longitudinal and transverse directions due to local damage to the sheath is studied.According to the corrosion state of the surface of the steel wire in the stay cable,the rust degree of the steel wire is graded.The shape and number of corrosion pits on the surface of the steel wire were counted,and the characteristics of the surface pits on the cable wire under the actual service state were studied.(2)Static tensile tests were conducted on steel wires of different corrosion grades to analyze the effect of different degrees of corrosion on the mechanical properties of the steel wire,combined with the fracture form and damage characteristics of the steel wire,and the characteristics of the pitting corrosion pits on the mechanical properties and damage formsof the steel wire influences.(3)Fatigue loading test was carried out on cables with different rust grades,to study the effect of corrosion on the fatigue life of cable stays under different rust grades,and SEM scanning was carried out to analyze the pitting corrosion The effect of pits on the fatigue fracture form,fatigue life and steel wire corrosion fatigue failure mechanism of steel wire is based on the equivalent cracking method and Paris crack propagation formula to predict and evaluate the remaining fatigue life of corroded steel wire,and explore the pitting corrosion pit and fatigue crack The influence of the initiation and expansion laws on the fatigue life of stay cable steel wire.