In order to investigate the influence mechanism of steel fiber content on the dynamic compression and tensile mechanical properties of concrete,this study conducted dynamic compression and dynamic Brazilian splitting tests on concrete samples with varying impact pressure and steel fiber volume contents(0%C50 element concrete,2%,3%,and 4%) using a Hopkinson pressure bar(SHPB) device.Additionally,highspeed photography was employed to reveal the dynamic evolution process of cracks.The test results demonstrate that under the same impact pressure,both the dynamic compressive strength and dynamic splitting tensile strength of steel fiber reinforced concrete samples exhibit a positive correlation with the content of steel fiber.Furthermore,there is also a positive correlation between energy absorption capacity and degree of crushing,indicating that steel fibers effectively inhibit concrete crushing while preventing excessive energy absorption and dissipation in these samples.The upper limit for energy absorption rate in steel fiber reinforced concrete samples ranges from 30% to 36%.Notably,compared to its effect on dynamic compressive strength,steel fibers significantly enhance the dynamic splitting tensile strength of concrete.For applications requiring highstrength or antiviolence characteristics in combination with costeffectiveness,technical controllability,and test data analysis;incorporating a reasonable range for toughening can be achieved by including 2%~3% steel fiber content into highstrength concrete.Moreover,it is important to note that the action mechanism of steel fibers differs when considering their effects on both dynamic splitting and compression failure in concrete samples.Steel fibers significantly impede crack propagation during dynamic splitting processes;however,separation between the fibers themselves leads to ineffective toughening during dynamic compression."