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Research on Elastic Modulus Conversion of Corroded Cables Considering Stress Concentration
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摘要: 拉索弹性模量换算法是一种通过对拉索弹性模量进行换算从而在整体斜拉桥结构分析中考虑拉索腐蚀效应的方法。然而该方法对拉索钢丝表面复杂蚀坑分布情况下的适用性存疑，且未考虑其在蚀坑附近应力集中较大时的适用性。通过对拉索钢丝表面蚀坑的有限元模拟，考虑两参量耦合关系，采用二元拟合方法联合拟合了蚀坑长短轴比、深度、数量、间距等参数与钢丝应力集中系数的关系，并验证了上述参数组合下弹性模量换算法的适用性，通过某斜拉桥成桥状态下拉索应力的对比，定义了该换算法的基本适用条件。结果表明：应力集中系数总体随着蚀坑长短轴比、蚀坑深度和蚀坑数量的增大而增大，随着蚀坑间距的增大而减小；弹性模量换算法可较好地适用于各蚀坑参数的组合工况并满足工程计算的精度要求，但不能直接适用于拉索局部应力值超出钢丝极限强度的情况。Abstract: The cable elastic modulus conversion method is a technique that incorporates cable corrosion effects into the analysis of the overall cable-stayed bridge structure by converting the cable elastic modulus. However， its applicability in cases with complex corrosion pits on the cable wire surface is questionable， and scenarios involving significant stress concentration near the pits are not considered. In this paper， through the finite element simulation of corrosion pits on the surface of a cable wire， the relationship between the major-to-minor axis length ratio， depth， number， and spacing of the pits and the stress intensity factor of the wire was fitted binarily with consideration of the coupling effects between each pair of parameters. The applicability of the cable elastic modulus conversion method under various combinations of these parameters was then verified. Furthermore， the basic applicable conditions of the conversion method were defined by comparing cable stresses in the completed state of a specific cable-stayed bridge. The results showed that the stress concentration factors increased with the major-to-minor axis length ratio， pit depth， and pit number， and decreased with pit spacing. The elastic modulus conversion method is well applicable to combined scenarios of various corrosion pit parameters and meets the accuracy requirements of engineering calculations. However， it cannot be directly used when the local cable stress surpasses the ultimate strength of the steel wires.
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