Fatigue Test And Reliability Analysis Of Basalt Fiber Concrete

Basalt fiber concrete is a new kind of concrete material by adding a certain amount of short-cut basalt fiber into the matrix of ordinary concrete.After adding a certain amount of basalt fiber into concrete,the overall mechanical properties of concrete are improved,especially the crack resistance of concrete.Basalt fiber has excellent mechanical properties and workability,and has good bonding effect with concrete matrix,so basalt fiber concrete has good engineering application prospect.At present,the study on static load performance of basalt fiber concrete is relatively mature,but the study on fatigue performance is relatively less.Therefore,when basalt fiber concrete is used in Bridges,it is questioned to some extent in this field as a component that bears alternating load.The fatigue life and deformation properties of concrete materials under cyclic loading are the basis for studying the fatigue performance of concrete structures.This paper mainly studies the fatigue performance of concrete with different basalt fiber content,which provides basis for scientific research and practical engineering application.The main contents are as follows:First of all,in order to find the optimal content of basalt fiber in the flexural tensile strength of concrete specimens,the prepared specimens were tested for flexural tensile strength by adding 0%,0.2%,0.3% and 0.4%basalt fiber by volume percentage in concrete.Based on the data,the loading value of the fatigue test was calculated and the uncertainty of the fold test was analyzed.It is found that the percentage increase of flexural strength is the highest when the fiber content is 0.3%.Moreover,the factor causing the highest uncertainty of test data is the repetition of test results,that is,the repeatability test.Secondly,two-parameter and three-parameter Weibull distribution are used to analyze the probability and statistical analysis of fatigue life respectively to predict the life at different confidence levels.The S-N curve and the P-S-N curve are also made.The probability statistical analysis shows that the fatigue life of specimens decreases with the increase of stress amplitude and increases with the increase of basalt fiber content.Then,the fatigue modulus of basalt fiber concrete is analyzed according to the fatigue test data,and the fatigue life of basalt fiber concrete is predicted according to this rule.The results show that the elastic modulus of the specimen presents three stages,the first and third stages vary greatly,and the second stage presents obvious linearity.The ratio of the predicted life to the actual life is less than 2,which indicates that the prediction result is more ideal.Finally,the maximum and minimum values of strain in cyclic loading are found in fatigue data,and their variation rules are analyzed.Then the hysteretic curve of the specimen is made according to the data,and the area of its hysteretic curve,namely the change rule of dissipative energy per unit volume,is calculated.The variation of maximum and minimum strain and dissipated energy per unit volume is similar to that of fatigue elastic modulus.