钢纤维混凝土动态劈拉行为细观数值分析OA

In order to reveal the dynamic splitting mechanical properties and failure characteristics of steel fiber reinforced concrete(SFRC),a mesoscopic model of SFRC including polyhedral aggregate,mortar matrix,interfacial transition zone(ITZ)and steel fiber was established based on the joint simulation method of MATLAB programming and LS-DYNA software.Considering the bond stress-slip behavior of steel fibers,the numerical simulation of the dynamic splitting process of split Hopkinson pressure bar(SHPB)under different impact velocities was further performed.The results show that the mesoscopic model constructed in this paper can effectively simulate the dynamic splitting performance and failure characteristics of SFRC,and the applicability of the model and the accuracy of material parameters are verified.As the impact velocity increases,the area of the wedge-shaped failure zone at the loading end of the specimen increases,and the width of the main crack at the center of the specimen increases significantly.Steel fiber inhibits crack propagation through bridging effect,slows down damage evolution,and significantly improves the splitting toughness of concrete.The internal energy time history curves of aggregate,mortar matrix and ITZ increase first and then decrease,and the peak internal energy of mortar is the highest,followed by ITZ and aggregate.The impact energy absorbed by the specimen is mostly used for crack initiation and propagation,and the kinetic energy accounts for about 5％.The peak internal energy and kinetic energy of aggregate,mortar matrix and ITZ in SFRC specimens are lower than those in PC specimens.Steel fiber changes the energy absorption and dissipation mode of concrete,and converts part of the failure energy into fiber pull-out energy.The results demonstrate that the interfacial transition zone is the weakest link for crack initiation and propagation under dynamic loading,and the uniformity of fiber distribution significantly influences its reinforcing effect,for which the optimization of fiber dispersion processes should be emphasized in engineering practice.