Experimental investigation on mechanical properties of steel fiber reinforced recycled aggregate concrete under uniaxial cyclic compression

The performance of steel fiber reinforced recycled concrete (SF-R-RAC) under cyclic loading plays an important role in studying the response of recycled concrete structures under earthquake. In this paper, the effects of three design variables— the replacement rate of recycled aggregate, the content of steel fiber (SF), and the loading rate— on the stress–strain relationship and mechanical properties of SF-R-RAC specimens under cyclic loading were investigated. The failure mode of SF-R-RAC under cyclic action was observed, and the law of the cyclic stress–strain curve was summarized. In addition, the influence of different design variables on stiffness degradation and hysteretic energy dissipation of specimens under cyclic loading was described, which reveals the plastic strain law of SF-R-RAC under cyclic action. Finally, a piecewise function was used to fit the envelope of the cyclic stress–strain curve. The results show that adding SF to the recycled concrete specimen improves its ductility under uniaxial cyclic loading, delays the stiffness degradation rate of the specimen, and greatly improves its cumulative energy consumption. In addition, a constitutive relation formula for the SF-R-RAC stress–strain curve expressed by SF content is proposed, and the fitting result is good. This investigation provides a theoretical basis and an experimental reference for further study of SF-R-RAC.