桥梁拉吊索用不锈钢钢丝腐蚀性能及斜拉索时变可靠度研究
Study on Corrosion Properties of Stainless Steel Wire for Cable Use and Time-variant Reliability of Stay Cable of Bridge

对零应力普通镀锌钢丝和施加0%，20%，30%，40%强度的应力不锈钢钢丝，分7，20，40 d进行中性盐雾试验，研究零应力普通镀锌钢丝和不同应力水平下不锈钢钢丝的质量损失率、强度、延性和断口形貌的变化。通过算例分析了分别采用普通镀锌钢丝和不锈钢钢丝作斜拉桥拉索时可靠指标随时间的变化。结果表明：零应力下普通镀锌钢丝的质量损失率是不锈钢钢丝的30倍以上；不锈钢钢丝的质量损失率随着应力的增加而增加，高应力下的不锈钢钢丝更容易腐蚀；短期腐蚀对钢丝的极限强度影响不大，不锈钢钢丝随着应力的增加延性变差；随着腐蚀的增加，普通镀锌钢丝和不锈钢钢丝的拉伸端口呈现出脆性增加的趋势，普通钢丝的端口形貌由微裂纹向长宽裂纹发展，而不锈钢钢丝由于腐蚀较轻，只是出现了微裂纹；采用普通镀锌钢丝作斜拉桥拉索时可靠指标随时间的下降速度比采用不锈钢钢丝快。
The ordinary galvanized steel wire with null stress and the stainless steel wires with stress level of 0%, 20%, 30%, 40% of their strength were exposed in neutral salt spray test for 7, 20, 40 d, respectively, and the mass loss rate, strength, ductility and fracture surface topography of stainless steel wires were studied. An example of cable stayed bridge was presented to showcase the reliability index of cable made of ordinary galvanized steel wire and stainless steel wires. The results show that the mass loss rate of ordinary galvanized steel wire is 30 times higher than that of stainless steel wire. The mass loss rate of stainless steel wire increases with the increase of stress level, which implies that the stainless steel wire is more easily corroded under high stress. Corrosion in short-term has little effect on the ultimate strength of the steel wire. However, the ductility of stainless steel wire decreases with the increase of stress level. Both the galvanized steel wire and stainless steel wire reveal higher brittleness in the tensile test. The fracture surface topography of galvanized steel wire develops from micro cracks to wide cracks, while the stainless steel wire develops only micro cracks because of lighter corrosion. The reduction rate of reliability index of cable of stainless steel wires with time is lesser than that of ordinary galvanized steel wire