| Suspension bridge has been favored by many people for its advantages,such as the ability of great span,flexible adaptability and mature construction technology.The main cable is the lifeline of the suspension bridge,and the sling is the component of locomotive between the main girder and the main cable.Corrosion is the main problem that affects the safety of main cables and suspender of suspension bridges.Strengthening the monitoring of cable system and exploring the technologies and methods of risk assessment cable corrosion of suspension bridges are the keys to safe operation and normal service of suspension bridges.This article was based on the construction of science and technology project of Ministry of Transport Science the Control of Operation Safety Risk and Demonstration for the Long Bridge in Use(Project Number: 2015318J30050).The experiment of accelerated corrosion of cable structure has launched over the corrosion situation of main cable and hanger of suspension bridges which are still in use.The method of evaluating the corrosion state of cables by using three axes magnetic field strength was established and the calculation method of corrosion risk probability of cable in suspension bridges which are under normal service condition also was studied.Combined with the particular project case,the corrosion condition of suspension bridge cable has been evaluated,and the risk probability of bridge was calculated.The main research work and conclusions are as follows:Firstly,the corrosion mechanism was studied of cable structure of suspension bridge.Through indoor electrochemical corrosion test,3 groups of steel strands and 5sets of wire ropes were accelerated corrosion.The three axes flux gate magnetometer is used to test the different stranded steel strands and wire ropes.The relationship between the three axes magnetic field strength and the corrosion weight loss rate of steel strand and steel wire rope with different corrosion degree has been established.Secondly,the method of major risk scenario assessment of suspension cable corrosion was studied.A probabilistic evaluation index system for cable corrosion risk was also established.Based on the field corrosion detection method and risk probability calculation of suspension bridge,the major risk scenarios for cable corrosion of suspension bridges were evaluated according to the evaluation method which make the cable corrosion risk probability as an index.Thirdly,the risk probability calculation method of cable corrosion for suspension bridges was studied.Probability factors and load probability factors of cable structure resistance are analyzed respectively.The resistance probability model and load probability model of cable structure under normal condition was established,and the risk assessment method of cable corrosion based on special detection and numerical simulation was established.Fourthly,the cable corrosion assessment method based on the field detection and finite element simulation of suspension bridge was developed.Based on the test of the corrosion of the main cable and sling,the risk probability of the suspension cable andthe main cable corrosion yield failure of the Baling River Bridge was analyzed according to the resistance probability model,the load probability model and the normal distribution curve of the probability model. |
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