Experimental investigation on the stress-strain behavior of steel fiber reinforced concrete subjected to uniaxial cyclic compression

The behavior of steel fiber reinforced concrete (SFRC) under cyclic loading plays an important role in prediction of SFRC structural response. This paper deals with the stress-strain behavior and damage evolution of SFRC under uniaxial cyclic compression. A total of 36 specimens are tested for different fiber volume fractions and aspect ratios. Acoustic emission (AE) technique is used to characterize the damage progression and reveal the failure mechanism of SFRC during the whole loading process. The results show that slight strength degradation for SFRC specimens under cyclic loading is observed in comparison with monotonic loading cases. The increase in volume fraction of steel fiber can lead to a remarkable decrease in the plastic strain accumulation as well as an increase in the elastic stiffness ratio, while the effect of fiber aspect ratio is undiscernable. In addition, it is indicated from the AE parameters analysis that the total AE activities of SFRC specimens are higher than that of plain concrete specimen and become greater with an increase in the fiber volume fraction, while the opposite is true for increasing the fiber aspect ratio. Meanwhile, as substantiated by AE, the failure of SFRC mainly demonstrates a shear cracking mode that is induced by fiber pull-out and fiber sliding events, the amount of which is proportional to both fiber volume fraction and aspect ratio. Finally, based on the test results of stiffness degradation, an analytical formulation for the damage evolution law of SFRC is developed and the prediction yields a close estimation of SFRC damage progression.