Experimental Study On Stray Current Corrosion And Fatigue Failure Of High Performance Concrete

In recent years,owing to the rapid development of our country's economy,in order to meet the needs of people travel fast,while speeding up the city construction pace,urban rail transit becomes the focus of people's attention.As a new city public transport system has become an important way to solve city traffic problems in recent years.And the rail beam in the interaction of steel corrosion and fatigue loading of concrete structure of life will be greatly reduced.The high altitude and drought in Xining area,the large temperature difference of climate and environment on rail transportation of high performance concrete cracking effect is serious,so the study on the law of the cracks in track beam under fatigue is necessary.This topic comes from the sub project of Xining railway traffic engineering concrete structure key technology research and demonstration(subject number: 2013-G-Q06A).Qinghai University research group undertakes a research on fatigue properties of rail beam.This project on the test beam fatigue loading test using 1000 kN fatigue testing machine;The fatigue test of the reinforced concrete Liangtong DC current by using dry cell is corroded by the steel bar corrosion.By analyzing the stress and failure modes of HPC rectangular and T-shaped beams,the following conclusions are obtained: There are obvious three-phase rules for deflection,crack width and strain change under static load and fatigue failure;HPC anti-corrosion and anti-fatigue properties are better than OPC and have a certain anti-crack performance in the late stage of loading;brine and stray current can accelerate corrosion of steel bars affects the life of concrete beams;Stirrups in concrete have a certain resistance to cracking;Fatigue failures are often caused by damage accumulation in the concrete;The average normal section strain of T-beam under static load and fatigue is in agreement with the flat section assumption.By studying the corrosion of steel bars corroded by various stress HPC beams,and the fatigue life and mechanical behavior failure mechanism of each stress ratio of the lower beams,the fatigue S-N curves of the test beams were plotted,and the S-N curve equations were fitted.The research results will provide a theoretical basis for evaluating the fatigue performance of HPC beams with low corrosion rate in Qinghai,so as to improve the durability and safety of concrete structures in the region and improve the service life of HPC structures.