Research On Mechanics Behavior And An-penetration Mechanism Of Steel Fiber Reinforced Concrete

Steel Fiber Reinforced Concrete (SFRC) composed of aggregate, cement and the radom-orientd steel fiber is a kind of multiphase and inhomogeneous composite material. SFRC is a useful engineering material and is used extensively for the defense engineering, since it has good mechanical behaviors and anti-penetration characteristics. In this dissertation, the mechanical behavior and anti-penetration mechanism of SFRC are studied systematically by experiments, theoretical analyses and numerical simulationsFirstly, the reinforced mechanism of SFRC is considered. According to the leading features of the stress-strain curve, the growing of damage in SFRC is subdivided into four stages, i.e. the pre-crack stage, the growing of pre-crack stage, the stable growing and initiation of crack and the unstable growing and uncontrolled initiation of cracks. The reinforced mechanism of SFRC corresponding to the stages mentioned above is analyzed in details from the point of view of composite material mechanics, fracture mechanics and interfacial mechanics.Then the dynamic and static mechanical behavior of SFRC is investigated by MTS and SHPB apparatus. The experimental results showed that SFRC is a material with obvious steel fiber reinforcing, strain-rate hardening and damage softening. The functions of fiber content and strain-rate on the mechanical behavior of SFRC are studied on the foundation of the experiment stress-strain curves. According to the basic characteristics of experimental curve, an empirical constitutive model is proposed in which the effect of steel fiber reinforcing and strain-rate hardening and damage softening are considered.Ballistic test is one of the most important research methods in the study of the anti-penetration capability of concrete. In the dissertation, the penetration experiments of SFRC are conducted by a semi-spherical head projectile launched by smooth-bore cannon. Three kinds of targets are used in the tests, in which the steel fiber content is 0.0%, 3.0% and 6.0% separately. Residual velocity of the projectile is measured and the failure modes of the target are observed and recorded. The results shown that...