Study On Life Prediction Method Of RC Bridge Under Coupled Corrosion-fatigue Effects

The reinforced concrete bridges in coastal areas are under two types of damagesall the year round. One is internal penetration of the rich chloride ion in the seawatertransporting from sea and air. In such corrosion environment, the reinforcement willbe corroded, which will reduce the bridge service life; the other is repeat loading ofthe oversize vehicles the in service bridges in the coastal areas have to suffer. Therepeat lading can easily cause the brittle fatigue damage lower than the static strengthof the bridge. These two types of damages exist in the same time and have the couplenature. It is so common to find the cases that the bridge structure damage andeconomy loss caused by the coupling of corrosion and fatigue loading home andabroad in recent years. Thus, it has become the hotspot to study the degeneration ofreinforced concrete performance under the coupling of corrosion and fatigue loading.The current domestic and abroad researches on degeneration of the reinforcedconcrete bridge under the coupling of corrosion environment and fatigue loading areconcluded comprehensively and systematically and the shortcomings of existingresearches are pointed out through analyzing the research results. Based on the results,the lifetime degeneration of the reinforced concrete bridge under the coupling ofcorrosion and fatigue loading is analyzed from the perspective of material and layer ofstructure. An analytical method of the lifetime of the reinforced bridge under thecoupling of corrosion and fatigue loading is proposed upon parametric multi-scalefinite element modeling technique and vehicle-bridge coupling vibration program toapply in engineering practice.1. Utilizing numerical simulation of two-dimensional modeling method, thedifferent rust pit shapes in the internal reinforced concrete beam and the variation ofthe mechanical property under different corrosion penetration are comparativelyanalyzed, which indicates that stress concentration becomes more serious as the rustpit gets deeper. Meanwhile, the quantitative result of reinforced non-uniformcorrosion effect on reinforced concrete structure mechanical property is obtained fromwidget hierarchy.2. The reinforced concrete bridge finite element model is built using parametricmulti-scale finite element modeling technique, which introduced the method of multi-scale finite element modeling for bridges.3. Based on bridge multi-scale modeling technique and vehicle-bridge couplingvibration program, the prediction method of the lifespan of the reinforced bridgeunder the coupling of corrosion and fatigue loading is proposed unifying the relatedtheories. The corrosion fatigue life of an grand bridge is analyzed through exampleanalysis, which explains the usage of the prediction methods of reinforced concretebridge lifespan mentioned in the paper and analyzes the variation of the bridgelifespan when the road conditions and vehicle speed change. The result indicates thatthe bridge lifespan is shorter when the road condition is worse; the bridge lifespan ishardly affected by the vehicle speed.4. The basic concept and related theories as well as application in reinforcedconcrete structural analysis of damage and fracture mechanics are introduced. Thebasic methods and procedures to predict the damage and fracture of reinforcedconcrete bridges’ life are discussed, which has laid a theory foundation for the furtherstudy.