| As a key component of modern long-span Bridges,cables are sensitive to environmental media,and the damage of the protection system is not easy to be checked.Therefore,corrosion is one of the focuses of bridge operation and maintenance.At present,the detection and monitoring of the health status of the cable during service mainly focuses on the damage and broken wire of the cable,while the detection and monitoring of its early corrosion is seldom studied.Due to the high sensitivity of resistance sensing technology in metal corrosion monitoring,this paper takes the lasso zinc aluminum alloy coating,high strength steel wire as the research object,has carried out based on the analysis of resistance sensor wire corrosion monitoring theory,the related parameters calibration experiment,high strength steel wire corrosion monitoring theory,and based on the theory of high strength steel wire corrosion monitoring experiment made a lasso corrosion sensors,the main work is as follows:(1)The error elimination method and resistance parallel model of high strength steel wire are presented.After analysis,the four-point measurement method is selected as the resistance measurement method in this test,and according to the error influencing factors of the measurement method(including thermoelectric potential,non-ohmic contact and resistance heating,etc.),the corresponding measurement error elimination method is given.At the same time,according to the material structure and element composition of high strength steel wire,the resistance parallel model of high strength steel wire with resistance method is proposed.(2)The corrosion judgment and resistance correction method of high strength steel wire based on resistance method are studied.The calculation theory of corrosion parameters of high strength steel wire and two methods to judge the corrosion stage of high strength steel wire based on resistance method are presented.According to the influencing factors of metal resistance(temperature and tension)and the characteristics of high strength steel wire resistance,a modification method of corrosion resistance of high strength steel wire is proposed.According to the actual working conditions of high strength steel wire in bridge,the resistance correction method is simplified.The influence of non-uniform corrosion on single metal corrosion monitoring by resistance method is proved mathematically,and its influence on high strength steel wire corrosion monitoring is predicted.(3)The calibration tests of the relevant parameters of the high strength steel wire resistance method were carried out.The datum and uncertainty of the required parameters of the whole high-strength steel wire,the coating of high-strength steel wire and the bare steel wire in the resistance corrosion monitoring were obtained,and the static tensile properties of the whole steel wire and the bare steel wire were compared,which provided data support for the resistance correction of the high-strength steel wire.(4)The comparative tests of resistance method and weight loss method under different corrosion conditions were carried out.Through the corrosion test of dilute hydrochloric acid,the reliability of the corrosion monitoring theory and the resistance correction method of high strength steel wire is verified.The influence of non-uniform corrosion on the corrosion monitoring of resistance method is verified by salt spray corrosion test,that is,in theory,the mass loss rate obtained by resistance method is always higher than the measured mass loss rate.In this experiment,the mean of this ratio was 1.76.(5)The design and test of the cable corrosion monitoring sensor based on the resistance sensor are completed.For the transition part of cable and anchor,a kind of cable corrosion sensor is designed and made.In order to reduce the measurement error of the sensor,the bare steel wire was used as the temperature compensation probe,and the reliability of the temperature compensation was verified by experiments.Through salt spray corrosion test of sensor and measuring the coating and the steel wire inside the average corrosion rate of steel in the salt fog test,the test results show that the production of cable corrosion sensors can well reflect the corrosion mass loss,probe sensors can represent a complete two over ten thousand of the steel wire corrosion,namely the average corrosion depth of 0.401 microns. |
