悬索桥主缆钢丝在持力状态下的表观腐蚀规律试验研究

Experimental Study on Apparent Corrosion Rule of Main Cable Steel Wires of Suspension Bridge in Holding Force State

针对悬索桥主缆钢丝在持力状态下的腐蚀规律问题,设计了一套稳定持荷的电解加速腐蚀试验装置,开展了悬索桥主缆钢丝在持力状态下的电解加速腐蚀试验。试验分别选取持力0,1 000,2 000和3 000με4个工况共60根直径5.25 mm的悬索桥主缆同类钢丝,分别测量0~4 d电解加速腐蚀后的钢丝质量和直径,分别研究了高强钢丝腐蚀后外观的变化规律问题、不同应力水平及腐蚀时间对高强钢丝平均质量损失率的影响问题以及腐蚀后高强钢丝最大截面损失率的影响问题,探讨了持力状态下主缆钢丝平均质量损失率和截面损失率随应变和时间增长的变化规律。结果表明:随着应变水平的增加,腐蚀时间的增长,持力状态下的钢丝腐蚀越明显,局部表征起伏越剧烈;持力状态下高强钢丝平均质量损失率随着时间的增长呈非线性增长,整体呈现出随着时间和应力水平的增长腐蚀速率变快的趋势;3 000με作用下持力钢丝电解加速腐蚀4 d质量损失与自然腐蚀420 d试验结果相近,且变化趋势一致;加速腐蚀情况下,3 000με钢丝平均质量损失率4 d是1 d的6.40倍,且1~4 d分别是2 000με下的1.17倍,1.22倍,2.27倍和3.02倍;最大截面损失率随着应变和时间的增加而增大,且与两变量相关性较好,可以考虑采用最大截面损失率作为核心中间变量来衡量主缆钢丝的腐蚀等级。

In order to found out the corrosion rule of the main cable steel wires of suspension bridge under status of holding force, a set of electrolytic accelerated corrosion test device with stable load is designed. The electrolytic accelerated corrosion test on the main cable steel wired of the suspension bridge in the state of holding force is carried out. Selecting a total of 60 same steel wires of the main cable of the suspension bridge with diameter of 5.25 mm under the working conditions of 0, 1 000, 2 000 and 3 000 με, the masses and diameters of the steel wires after 0-4 days of electrolysis accelerated corrosion are measured respectively. The changes of appearance of high-strength steel wire after corrosion, the influence of different stress levels and corrosion time on the average mass loss rate of high-strength steel wires and the maximum section loss rate of high-strength steel wires after corrosion are studied. The change rules of the average mass loss rate and cross-sectional loss rate of the main cable steel wires with strain and time growth are discussed. The result shows that(1) with the increase of strain level and corrosion time, the more obvious the corrosion of steel wires in holding force state, the more intense the fluctuation of local characterization;(2) the average mass loss rate of high-strength steel wires in holding force state increases nonlinearly with the increase of time, and the overall trend of corrosion rate increases with the increase of time and stress level;(3) the mass loss of the steel wires with holding force of 3 000 με after 4 days of accelerated electrolytic corrosion is similar to the test result of 420 days of natural corrosion, and the change trend is consistent;(4) under accelerated corrosion condition, the average mass loss rate of steel wires with holding force of 3 000 με after 4 days of accelerated electrolytic corrosion is 6.40 times as large as that of 1 day, and the average mass loss rates of steel wires with 3 000 με after 1-4 days of accelerated electrolytic corrosion are 1.17, 1.22, 2.27, 3.02 times as large as those of 2 000 με respectively;(5) the maximum section loss rate increases with the increase of strain and time, and it has a good correlation with these 2 variables, therefore, the maximum section loss rate can be considered as the core intermediate variable to measure the corrosion grade of main cable steel wires.