Effect Of Tension On Corrosion Behavior Of Steel Strand In Cable Structure Of Cable-stayed Bridge

The cable-stayed bridge has many advantages such as long span, light and beautiful structure, well dynamical stability of air, single framework style and so on. Consequently, it has become the leading style in the present bridge construction. Because cables are the key components of cable-stayed bridge, the cable corrosion directly decides the security of the bridge. Owing to bearing alternative load and long exposure in natural environment, cables are easily corroded and wrecked, especially in the serious polluted regions and seashore. The bridge would even collapse if it had been corroded and wrecked severely, which could cause great losses in lives and wealth. Therefore, it is important to study cable's corrosion behaviors and corrosion resistance processes in order to increase endurance and security of bridge construction.The corrosion behaviors of galvanized steel wire under different tention were studied by using massloss measurement, linear polarization method and Tafel polarization curve. With the XRD, TG-DTA and optical microscope, the surfacial morphology of corrosive cables had been achieved. Some conclusions of this dissertation were drawn as follows:1. The result of corrosion research in 5%NaCl solution of pH=7 shows: without tension, corrosion rate and corrosion current density of galvanized steel wire are the least, but the polarization resistance is the largest. While with 22kN tension, corrosion rate and corrosion current density of galvanized steel wire are the largest, but the polarization resistance is the least.In this case, the corrosion rate, corrosion current density and polarization resistance are 0.3357 g·m^-2h^-1, 1.846×10^-5 A·cm^-2 and 808·, respectively.2. The result of corrosion research in 5%NaCl solution of pH=3.5 shows that corrosion rate or corrosion current density of galvanized steel wire increase, and polarization resistance declines with increase of the tension. There no exsit linear relation in resulting parameters.3. The result of corrosion experiments in simulate acid rain are shown as follows: when the tension imposed on galvanized steel wire are 0kN, 5kN, 10kN, 15kN, 20kN and 22kN, corresponding corrosion rates are 0.03175 g·m^-2h^-1, 0.0565 g·m^-2h^-1, 0.08318 g·m^-2h^-1, 0.1094 g·m^-2h^-1, 0.1417 g·m^-2h^-1 and 0.158 g·m^-2h^-1respectively, and the corrosion current densities are 1.224×10^-6A·cm^-2 1.820×10^-6A·cm^-2, 2.284×10^-6A·cm^-2, 2.885×10^-6A·cm^-2, 4.217×10^-6A·cm^-2and 1.142×10^-5A·cm^-2 respectively, and the polarization resistances of galvanized steel wire are 3730Ω, 2967Ω, 2493Ω, 1833Ω, 1301Ωand 990Ωrespectively.4. Accelerated corrosion tests are conducted to find out how these different tensions inside the cable affect the corrosion performanceof galvanized steel wires. The white rust of galvanized steel wires at different tension appears within one cycle, the red rust appears after 16 cycles at 15～22kN tension, and 23 cycles at 0, 10kN tension, and its corrosion products mainly consist of Zn₅Cl₂(OH)₈·H₂O,Zn₄(CO₃)(OH)₆·H₂O and ZnO.