Analysis on the impact resistance of steel fiber reinforced recycled aggregate concrete

The use of recycled aggregates and the addition of steel fibers make steel fiber reinforced recycled aggregate concrete (SFRRAC) an environment-friendly and high-performance building material. To investigate the dynamic mechanical properties of SFRRAC, this study aims to reveal the failure mechanism under impact loads and analyze the internal forces acting on the steel fiber within the recycled aggregate concrete (RAC). The impact performances of SFRRAC under varying strain rates was simulated using the proposed finite element model. The SFRRAC with 1.5 % steel fiber content and 50 % replacement ratio of recycled coarse aggregate was analyzed under the impact pressure of 0.3 MPa, 0.4 MPa, 0.5 MPa and 0.6 MPa, respectively. The research shows that the matrix element of the RAC is mainly subjected to compressive strain in the stress-time curve.The steel fiber is mainly compressive at the initial stage of loading, gradually changing into partially tension and partially compression, and tensile at the later stage. The steel fiber parallel to the impact direction experiences primarily compressive stress, while the steel fiber perpendicular to the impact direction is subjected to mainly tensile stress. Initially, the inclined steel fiber experiences primarily compressive stress, transitioning to mainly tensile stress in the later stage. The study provides basic support for dynamic design of such materials in practical engineering.