Study On Fatigue Performance And Fatigue Life Of Concrete Under Corrosive Environment

With the large-scale construction and development of high-speed railways,the demand for concrete in railway engineering is increasing.At the same time,high-speed railways are subjected to long-term loads during open-air service,which challenges the safety and durability of concrete materials.Therefore,it is necessary to explore the corrosion fatigue performance of concrete materials in different corrosive environments,further ensure the durability of concrete structures,reduce the impact of corrosion fatigue on concrete structures,and further explore the corrosion fatigue of concrete.This paper takes the high-speed railway concrete material as the research content,and analyzes the degradation law of corrosion damage at the macro level by simulating the acid rain corrosion environment.Corrosion fatigue tests were carried out on concrete specimens to analyze the degradation performance and fatigue failure law of concrete under the action of corrosion fatigue.The fatigue equation of concrete under the action of different factors was established to further explore the positive fatigue effect mechanism of concrete.Combined with Weibull distribution theory,the fatigue life and fatigue equation under different failure probabilities are explored.The following main results were obtained through the research:(1)Aiming at the acid rain corrosive environment in the south,a simulated acid rain solution was used for the test.The concrete specimens with corrosion periods of 0 month,3months,6 months and 9 months were observed and tested to explore the effect of corrosion on the macroscopic properties of concrete.The test content includes appearance shape,quality,dynamic elastic modulus,saturated surface water absorption and flexural tensile strength.(2)For concrete under different corrosion cycles,the stress levels of 0.55,0.60,and 0.65 were selected for bending fatigue tests.The failure patterns,stress-strain curves and fatigue life of concrete under different factors in the fatigue process were analyzed,and the influencing factors were discussed.The corresponding fatigue equation is established by using singlelogarithmic and double-logarithmic curves,and the corrosion mechanism of concrete fatigue life is analyzed.(3)The Weibull distribution theory is used to analyze the fatigue life under different factors,and the linear regression coefficient and correlation coefficient are used to judge whether there is a linear relationship.At the same time,the influence of different failure probabilities on fatigue life is considered,and the fatigue life and fatigue equations under different failure probabilities are calculated,and the S-N curve under different failure probabilities is established,namely the P-S-N curve.