Research On Mechanical Properties Of Prestressed Steam-cured Concrete Bridge Corroded In High-speed Railway

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 facility plays a very important role in the high-speed railway. Some huge economical loss and social impact would be made, if the train operation is 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) According to the similarity theory, complete design of dimensions and reinforcement of the model; develop the corrosion program of the prestressed reinforcement, according to Faraday’s law, calculate conduction time, test the corrosion potential of the prestressed reinforcement by GECOR8while being electrified;(2) Develop the static load test program. The test are carried out on the steam-cured concrete beams with different corrosion rate. Obtain the failure modes and crack development of the models. Study the variation regularities of cracking load, ultimate load, mid-span deflection, concrete strain, steel strain and so on, according to different corrosion rates of the prestressed reinforcement;(3) Study the fatigue properties after corrosion of the prestressed reinforcement by the experiment. Analyze the variation regularities of failure modes, fatigue life, mid-span deflection, concrete strain and steel strain of the models according to different corrosion rates;(4) According to damage mechanics theory and experimental data, obtain evolutional law of damage variable as a function of fatigue life. Put forward a new damage variable formula, the uneven distribution of the fatigue life is concerned, and verify it.