Research On Damage Degradation Of Main Cable Wire Of Suspension Bridge In Corrosive Environment

Because the suspension bridge can cross the strait and other complex terrain,it is the first choice for the construction of large-span bridges.The main cable is the main load-bearing member of the suspension bridge.Once the fault occurs,it cannot be replaced,which seriously affects the safety of the bridge operation.Therefore,in order to study the main cable of the suspension bridge in the corrosive environment.The law of damage deterioration is based on the Nanjing Fourth Bridge.The main cable is tested by electrochemical test and static tensile test with high-strength galvanized steel wire and base steel wire as test materials.Full-bridge simulation is carried out using MIDAS CIVIL numerical software.The damage deterioration law and reliability change under corrosive environment are studied.The variation law of damage degradation of main cable under different corrosion conditions is obtained.On this basis,the reliability index determination method is proposed.The main innovative research results are:(1)Electrochemical experiment:(1)Corrosion single factor: The corrosion rate of the base steel wire in the main cable material is 1.91 times that of the galvanized steel wire;the influence of the NaCl concentration on the corrosion rate of the steel wire has a critical value of3.5%.(2)Corrosion multi-factor: temperature and NaCl concentration have greater influence on corrosion rate of steel wire than pH value,but pH value is significant in solution with low temperature and low NaCl concentration,and there is interaction between pH value and NaCl concentration;(2)Static tensile test study:The ratio of the three-dimensional size parameter of the maximum etch pit of the steel wire to the average corrosion depth is log-normally distributed at a level of 0.05 significance;The relationship between elongation,modulus of elasticity,ultimate strength,yield strength and average corrosion depth of galvanized steel wire and matrix steel wire is proposed;(3)Numerical simulation study:The critical position stress of the main cable is symmetrically distributed except for anchoring and other locations outside the tower,and the stress at the top of the tower reaches a maximum;The formula for calculating the reliability index of the full-bridge main cable under corrosive environment is proposed.There are 75 graphs,26 tables and 98 references in this paper.