The Mechanical Model For Fiber Reinforced Concrete Based On Meso-scale

Compared with normal concrete,fiber reinforced concrete(FRC)is widely used in civil engineering due to its excellent ability to resist cracks and deformation.Studies have shown that the reinforcement efficiency of short fibers in concrete not only depends on their properties and content,but also influenced by their distribution in concrete.In order to further determine these effects,this paper studied the distribution of short glass fibers in concrete based on Nano-CT X-ray imaging technology.Simpleware image processing software was used to obtain the three-dimensional spatial coordinates of the chopped glass fibers in the scanned specimen,and the distribution model of the chopped glass fibers in the concrete matrix were established based on statistical principles.Secondly,based on the obtained distribution law of glass fibers in concrete,the author combined python language and finite element software ABAQUS to establish a three-dimensional mechanical model of FRC based on mesoscale.The model considers three components including chopped glass fiber,concrete matrix and the interface between the two.In order to ensure the calculation efficiency,a mechanical model with a size of 1mm×1mm×1mm was selected to analyze the split tensile performance and cubic compression performance of FRC.The analysis results are in good agreement with the test results,verified the rationality of this model.Finally,this paper further used this mesomechanical model,and considers the effects of mesoscopic factors such as interfacial bonding properties,fiber content,and matrix strength on the macroscopic mechanical properties and failure process of fiber reinforced concrete.At the same time,the effect of the distribution of chopped fibers on the macro-destructive behavior of fiber-reinforced concrete was analyzed using a three-dimensional mesomechanical model of 100mm×100mm×100mm.The specific research contents are as follows:(1)Through the Nano-CT X-ray scanning test,the chopped glass fiber reinforced concrete(GFRC)sample was scanned,and the scanned image was processed using Simpleware image processing software to obtain the spatial coordinates of the chopped glass fiber in the concrete matrix,and then the statistical software SPSS was used to analyze the fiber coordinates,the distribution model and probability distribution function of chopped glass fibers in the concrete matrix were established.The test results show that the chopped glass fiber in the concrete matrix is mostly parallel to a plane,and the angle between the fiber and each coordinate axis satisfies the exponential distribution in the Cartesian coordinate system.This part corresponds to the second chapter of the paper.(2)Based on the finite element software ABAQUS,a three-dimensional mesomechanical model of FRC was established.The three-phase components were considered,including fibers,concrete matrix and interface between the two,and combined with Python language,the chopped fiber was enabled exponential distribution.In order to verify the rationality of the model,the mechanical model was used to numerically simulate the compression and splitting tensile failure behavior of the FRC.The numerical results obtained are in good agreement with the experimental results,verifying the established Take a closer look at the rationality of the mechanical model.This part corresponds to the third chapter of the paper.(3)The author further studied the influence of several factors on the macro-mechanical properties of the FRC,included the influences of fiber content,concrete matrix strength,interfacial bond strength and fiber distribution.The results show that the addition of fibers has little effect on the compressive strength of FRC.The gain effect of fiber on the splitting tensile strength of FRC from small to large is in order of vertical distribution,random distribution,exponential distribution and horizontal distribution;The splitting tensile strength of FRC will increase first and then decrease with the increase of FRC,and follow the matrix the strength wae increased;The split tensile strength of FRC increases with the increase of the interface property between the fiber and the matrix.This study makes people more clearly understand the mechanism of fiber in FRC and its effect on the macro-mechanical properties of FRC.The research results obtained are a powerful supplement to the mesomechanical study of FRC and provide theoretical guidance for the analysis of other types of concrete.