Study On Dynamic Properties Of Steel Fiber Reinforced High Strength Concrete

Steel fiber reinforced concrete (SFRC) is made of hydraulic cements containing fine aggregate, coarse aggregate, and with randomly oriented steel fibers. SFRC has been used extensively as a construction material for buildings, bridges, tunnels and nuclear reactor containment. In the hardened process of concrete, the steel fiber can reduce the crack number, shorten the crack length. In the loading process, the crack-bridging behavior of the steel fiber can postpone crack initiation and restrain the propagation of crack. SFRC has superior static and dynamic behavior compare with the plain concrete for above reasons.In this thesis, the history and present state of the study on the dynamic mechanics properties of concrete and the developing history of rate-dependent constitutive models of concrete in domestic and aboard were reviewed first according to extensive literature. Because of the difficulty of concrete high strain rate experimental techniques, there are many disputes about how to describe the dynamic mechanics properties of concrete. Split Hopkinson pressure bar (SHPB) set is one of the reliable equipments for high strain rate material experiment. The researchs on SHPB experiments of concrete were summarized.One of the focuses of this thesis is on the rate-dependent behavior of steel fiber reinforced high strength concrete. The uniaxial compression experiments under five different strain rates of quasi-static loading, quasi-dynamic loading and impact on steel fiber reinforced high strength concrete with three grade(C60, C90, C100) and with four fiber fractions (0%, 2%, 4%, 6%) were carried out. The influences of input pulse, range of strain rate, new experimental techniques, date processing method, end frictional effect and inertial effect of the specimen were taken into account in the SHPB experiment to ensure the precision required. On this basis, the experimental results were analyzed comprehensively from the strain rate effect of main mechanics parameters (compressive strength, peak strain, toughness, elastic modulus), the mechanism of strain-rate hardening of concrete, the mechanism of reinforcing effect and toughening effect of steel fiber. The relationship between dynamic strength...