Numerical Simulation Of Meso-structure And Failure Process Of Fiber Reinforced Concrete

With the advantage of high specific ductile and high toughness, fiber reinforcedconcrete(FRC) has been more and more widely used in the field of civil engineering. Theresearches on the mature mesoscopic models of FRC are absent, while main study are focusedon the macroscopic experiments and qualitative analyses. The quantitative analyses of therelationship between the meso-structural and macroscopic response are even less. In thispaper mesoscopic mechanics model of fiber concrete was built from the perspective ofmesoscopic. Based on meso-damage mechanism theory and numerical simulation technology,the crack growth and the failure mechanism during the process of fiber concretes damage andfracture were analyzed in this paper.FRC is the three-phase heterogeneous composite materials consisting of coarse aggregate,fiber mortar matrix and interface transition zone between them on the mesoscopic level. ByMotor-Carlo random sampling method, the shape geometry information of aggregate inconcrete was received. The FRC meso-structure numerical model of different particle shapeand content of aggregate was built by the algorithm of concrete aggregate random insertion.The random horizontal cross-section of the concrete specimen was processed by thedigital image technology of watershed segmentation and morphological operations. Then theprecise2-D concrete digital model was made based the processed image through figure vectortechnique. To investigate the shape feature of internal coarse aggregate in concrete, theroundness, elongation ratio and Blaschke ratio of coarse aggregate were analyzed by thestatistical method. The chief axis slope of coarse aggregate and grade curve were analyzed toinvestigate the spatial distribution of internal coarse aggregate in concrete.The constitutive relationships of the meso-structure that describe mechanicalcharacteristics were established, based on the result of indoor experiment and theoreticalresearch. The numerical simulation experiments of uniaxial compression and flexural tests ofFRC were launched by the finite element technology. The results can better reflect thestress-strain characteristics and the process of damage and fracture under different stress state. The influence of particle shape and content of coarse aggregate on mechanical behaviorof FRC was analyzed by numerical experiments. The results showed that, the shape of coarseaggregate has greater significant influence on flexural strength of FRC than the compressivestrength. The compressive and flexural strength are significantly improved with coarseaggregate content increased, while the risk of fragile failure is increased.