Degradation State Research Of High-strength Steel Wires In Corrosive Conditions

Cable inspections revealed that severely corrosion of steel wires, caused bycontinuous aggression of environment, is one of the main failure mechanisms ofcables. The long-term deterioration process of steel wires in the cables considerssimultaneously the uniform and pitting corrosion and the corrosion fatigue inducedby both environmental attack and cyclic loading. The accelerated corrosionexperiments were conducted to produce different corrosion levels of high-strengthsteel wires and evaluate the variation in the uniform and pitting corrosion depths ofhigh-strength steel wires over time. The measured uniform corrosion depth followeda lognormal distribution with time-dependent corrosion variables at both the zinccoating corrosion stage and the steel corrosion stage. The block’s maximum pittingfactors from different exposure time were proved to be drawn from the sameunderlying continuous population and followed Gumbel distribution. The regressionmodels of the scale and location parameter with increased surface area wereobtained based on experimental block’s maximum pitting factors. The extreme valuedistribution of the pit depth of corroding steel wires could be predicted by thedeveloped statistical uniform and pitting factor models. The regression models ofmechanical properties for high-strength wires were also investigated. Thedeterioration conditions are subsequently assessed in a probabilistic way, such asyield strength, ultimate strength, elastic modulus, etc. Simultaneously, relatedexperiments were conducted to explore the consistency between the laboratory testresults and the degradation state of wires in the cables replaced from real bridgestructures.In this paper, both theoretical and experimental researches for high-strengthwires under laboratory and real service conditions are systematically conducted,providing theoretical and experimental basis to protect service performance andsafety level of long-span cable-stayed bridges, which has important socialsignificance.