Studies On Interaction Between Loading And Environment On Corrosion Fatigue Properties Of Prestressed Concrete Beams

Abstract:The characteristics of high-speed rail, high speed, high comfort, high security and high-density continuous operations, have put forward strict requirements for the railway line. Bridge structure as a transport facilities plays a very important role in the high-speed rail. Some huge economical loss and social impact would be made, if the train operation was interrupted. Bridge structure occupy a large percentage of the high speed railway line, therefore, the durability research of bridge structures in our country has become the technology difficulties in the high-speed railway construction. At present,32m prestressed steam-cured concrete box girders are used mostly in China’s High Speed Railway Bridge. In the beam, prestressed reinforcement is in a high stress state for a long time. It is particularly sensitive to the environmental corrosion. There will be the possibility of failure, once the corrosion of prestressed reinforcement occurred. This thesis takes32m prestressed steam-cured concrete bridge as the research object, after the corrosion of prestressed reinforcement, the mechanical properties of prestressed steam-cured bridge is studied through the model test. The main works of this thesis are listed as follows:(1) This thesis takes the32m prestressed steam-cured concrete bridge as the research object, according to the similarity theory, design the model; develop the corrosion program of the prestressed reinforcement, according to Faraday’s law, calculate conduction time, test corrosion potential of the prestressed reinforcement and validate the corrosion condition of the model beams;(2) In the third chapter, develop the static load test program. The test are carried out on the steam-cured concrete beams with different corrosion rate. Observe and analyse the failure modes and crack development of the models. Measure and analyze the cracking load, ultimate load, mid-span deflection, concrete strain, steel strain and so on. The variation regularities of static properties according to different corrosion rates of the prestressed reinforcement are studied;(3)Develop the constant amplitude fatigue test program and the test is carried out on the steam-cured concrete beams with different corrosion rate. Analyze the failure modes of the model with the variation of the corrosion rate. Determine the fatigue life of the model and mid-span deflection, measure the concrete strain, steel strain. According to the experimental data, fit a curve to the residual deflection, study the variation regularities of the residual deflection according to different corrosion rates.