Experimental study on impact resistance and dynamic constitutive relation of steel fiber reinforced recycled aggregate concrete

This study investigates the dynamic mechanical property and constitutive relation for steel fiber reinforced recycled aggregate concrete (SFRRAC). 15 groups of cylinder specimens were designed for SHPB impact resistance test with the change parameters of steel fiber (SF)content, replacement ratios of recycled coarse aggregate and impact pressure. The failure modes of the specimens were observed, and dynamic stress-strain curves of SFRRAC under different impact pressures were measured. The effect of changing parameters on dynamic peak stress, peak strain and energy dissipation performance and dynamic strength growth factor (DIF) were analyzed. The results revealed that the failure mode of SFRRAC is axial splitting failure. The peak strain, peak stress and energy dissipation of the specimens increase with the increase of SF content. At impact pressure of 0.6 MPa, the peak strain of the specimen increases the most. The peak stress of the specimens increases with the increase of the impact pressure, when the impact pressure increases from 0.4 MPa to 0.5 MPa, the peak stress of R0SF1 specimen sees the most substantial increase, reaching up to 15.78 %. As the of recycled coarse aggregate replacement ratio increased, the peak stress and energy consumption continuously decrease, at SF content of 0.5 %, the peak stress of the specimen decreases most obviously under the same impact pressure. The dynamic damage constitutive model of SFRRAC is proposed by introducing the damage factors which follow Weibull distribution and considering the influences of replacement ratios, SF content, and strain ratios.