Analysis Of Interfacial Bonding Properties Of Cement-based Materials With Steel Fibers Based On Cohesive Zone Model

Steel fiber reinforced concrete has been widely used in construction,water conservancy,bridges and other projects for its excellent performance.The addition of steel fiber in the concrete matrix can improve the ductility,toughness,tensile strength,shock resistance and crack resistance of concrete matrix.However,due to the weak interface between concrete and fiber,the strength and toughness of the steel fibers cannot be fully realized.As the core of the micro mechanical properties of steel fiber concrete,the interfacial adhesive property is usually measured by fiber pull-out test.But there are some limitations only through the test.In this paper,ABAQUS is used to study the whole process of pulling out the steel fiber from the concrete matrix based on the Cohesive Zone Model(CZM),which provides a reference for the study of fracture characteristics of the steel fiber reinforced concrete.In this paper,a three-phase finite element model of steel fiber pull-out from the concrete matrix is established based on the Cohesive Zone Model.A cohesive element is set up between the steel fiber and the concrete matrix to simulate the interface layer.The cohesive parameters of steel fiber pull-out from the concrete matrix were tested and verified by the test data.The influence of two cohesive force model parameters,fracture energy and maximum stress,on the pullout characteristics of steel fiber is studied.The method of selecting cohesive strength parameter is given,and obtained the cohesive parameters of steel fiber pull-out from the concrete.Secondly,cohesive elements are used to simulate the interfacial layer between the steel fiber and the concrete matrix.Establish a finite element model of straight steel fiber pull-out from the concrete matrix.based on the cohesive parameters of the steel fiber concrete selected by the above method.The distribution of shear stress and Von Mises Stress in the interface layer is analyzed.A finite element model is established to analyze the influence of three factors,interface elastic modulus,steel fiber embedment depth and steel fiber slenderness ratio,on interfacial stress.The effects of interface elastic modulus,steel fiber embedding depth and aspect ratio of steel fiber on the axial drawing properties of steel fiber were analyzed.Finally,based on the cohesive force parameters of the steel fiber concrete selected by the above method,the pull-out characteristics of steel fiber are analyzed.The influence of fiber type,fiber embedment angle,interface layer thickness and volume fraction of steel fiber on drawing characteristics was a nalyzed by finite element model.Then the influence of different factors on the tensile properties of steel fiber was obtained.