| Cable stayed bridge is becoming one of the popular bridge styles in the modern bridge construction due to its distinguished advantages such as single framework, well aerodynamic stability and relative light weight with a long span and so on. Cables are the important components which endure most of the loads and the weight of the bridge, and thus the whole bridge's safety and service life is greatly impacted by the cables'durability. Generally, cables of the bridge always endure alternative loads, and they are exposed to the air, the steel wires in the cable are prone to corrosion especially in SO42-, Cl- and other corrosive media contaminated environment, and thus the safety and life-span of the bridge will be greatly influenced, and even may lead to serious safety accident and economic losses. Therefore, it is meaningful to study the corrosion behavior and corrosion prevention methods of the steel wires in the bridge cables, which will contribute to the improvement of the bridge durability and safety.In this paper, Tafel linear extrapolation method and AC impedance technology were employed to study the influence of tensile stress and temperature on the corrosion behavior of hot-dip galvanized steel bridge wires, iridescent passivate electro-galvanized steel wires, and electroplated three-nickel /chromium steel wires in the simulated acid rain solution. Silane and cerous nitrate modified silane layers were prepared using sol-gel method and then dip-coated on the galvanized steel wires'surface, and corrosion behavior in the simulated acid rain solution were studied. Corrosion behavior of the galvanized steel wires with PE sheathing in the simulated acid rain fog were researched using Salt Spray Test, and hydrogen content of the samples were analyzed by LECO RH402. Main conclusions are as follows:①State of both domestic and oversea cable-stayed bridge development, hazards of cable steel wires'corrosion and its relevant protection methods, research work about cable steel wires'corrosion and ways of corroded cables'residual service life estimation methods were overviewed.②Corrosion current densities of hot-dip galvanized steel wire and iridescent passivate electro-galvanized steel wire in 60℃simulated acid rain solution under 1100MPa tensile stress were 27.95μA·cm-2 and 53.45μA·cm-2, respectively 4.5 and 3.8 times larger than their corrosion rates in room temperature simulated acid rain solution and without tensile stress. While for the electroplated three-nickel/chromium steel wire corroded in 60℃simulated acid rain solution, peak value appeared as 0.21μA·cm-2 when tensile stress was 600MPa, was 2.5 times larger compared with the corrosion rate obtained in room temperature simulated acid rain solution and without tensile stress. White grains formed around the pores when the hot-dip galvanized steel wire corroded at 60℃, while corroded under room temperature porous film emerged on the steel wire surface. For the iridescent passivate electro-galvanized steel wire corroded, the passivating film cracked. Pores against to the base were generated when corroded at 60℃under 1100MPa for the electroplated three-nickel chromium steel wire.③Corrosion potential of the hot-dip galvanized steel wire moved to the positive when coated with VS, and its anodic oxidation process was inhibited, protection efficiency reached 41.4%. With the increasing of the amount of cerium nitrate in the VS coating, corrosion potential turned more positive, corrosion rate became much slower. Protection efficiency reached 86.9% when the content of cerium nitrate in VS coating was 0.5wt.%.④Corrosion rates of the hot-dip galvanized steel wires exposed to 35℃and 50℃acid fog under 1100MPa tensile stress were 3.6mg·dm-2·d-1 and 4.3mg·dm-2·d-1, respectively 1.6 and 1.9 times larger than its relevant values obtained without tensile stress. This result showed that corrosion rates of the hot-dip galvanized steel wires increased with the increasing of tensile stress when exposed to the same temperature environment. While under the same tensile stress, red rust generating period of the galvanized steel wires shortened and corrosion became more severe with the increasing of environment temperature.⑤Results showed the outer layer galvanized steel wires'local zinc coating depleted after exposing to the Salt Spray Test for 2.5 months. And corrosion of the galvanized steel wires mainly along the outer layer of the cable, while the inner layer steel wires kept well during the test period. Hydrogen evolved on the steel wires'surface during the test period, hydrogen concentration was 4.50 ppm with the exposure time of 3 months, 1.8 times larger than the relevant value of the uncorroded steel wires. Main corrosion product after 2 months was 3Zn(OH)2·ZnSO4·5H2O, and a small amount of Zn5(OH)6(CO3)2 and ZnFe4(SO4)6(OH)2·18H2O. While after 3 months corrosion, corrosion products were mainly ZnSO3·2H2O and Fe6(OH)12CO3 , besides, a small amount of Zn7(CO3)2(OH)10,3Zn(OH)2?ZnSO4?3H2O were also detected.⑥Bridge cable residual service life prediction mathematic model was built using modifying factors corrected method. And according to the corrosion rates of galvanized steel wires and bare steel wires obtained in the accelerated test, and the natural corrosion data, the cable residual service life was estimated as 14.6 a.
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