Experimental Study On Fatigue Performance Of Beams Under Alternating Load Coupling With Corrosive Environment

Since the thirties of the20th century, although modern new materials and components keep innovating, reinforced concrete structure is still most widely used in civil, roads, bridges and other projects. However, concrete structures near the coast are under repeated vehicles load or dynamic load while suffer from atmospheric and marine environment at the same time. The coupled action of alternating load and corrosion environment lead to the damage of those structures. In this paper, research are done to study the durability of concrete beams under the the corrosion environment combined with different load type,analyzes the process and results of corrosion fatigue. The corrosion potential of steels and stiffness of the beam are measured.Besides the penetration law of chloridion are studied.The first chapter gives a comprehensive description of the research background, introduces research both at home and abroad about the durability of concrete beams under the the corrosion environment combined with load. And a conclusion of theory of reinforced concrete structures’ corrosion fatigue and the fatigue damage accumulation are done. According to the domestic and foreign research results about fatigue, corrosion, fatigue life change rule and influence factors were analyzed. At last, the main work content of this paper is proposed.The second chapter introduces design of the experiment, including the beam design and manufacture process, material performance test, the main test content and test devices. Loading device, data acquisition equipment, test methods and arrangement of measuring points of the test are given.The third chapter introduces the test of ultimate bearing capacity of beams, as the standard of the following experiment. The beam under constant load and chlorine salt environment are tested, to determine the long-term deflection when serving, corrosion potential, crack development change rule. Finally find that the development of deflection is a slow and long-term process.The fourth chapter has carried on the fatigue test of reinforced concrete beam under air and chlorine salt environment, the fatigue corrosion process and failure pattern of beams are analyzed and described. The results show that the coupling of alternating load and corrosion environment can largely reduces the fatigue life of beams. The steel corrosion potential measurement and analysis under corrosive environment is done to explore the law of steel corrosion changing with the load. In the process of fatigue corrosion test, the natural frequency of beams are tested to analysis the rigidity changes and beam damage degree. Still, the concentration of chlorine salt along the depth direction of the beams were determined, the test is to explore the diffusion rate of chloride ion in different kind of environment and loads.Chapter5summarizes the research work of this article comprehensively, and the test process are analyzed, at the same time give opinions for the continue studies to carry out about this topic in the future.