Study of the damage indices of concrete members reinforced with high-strength steel

The effects of high-strength steel (HSS) on the damage indices (DIs) of four special moment frames and three beam–column connection (BCC) specimens under cyclical loading were experimentally studied. The specimens with HSS rebars (with yield strengths of 500 MPa and 580 MPa) were designed and constructed based on the special seismic provisions of ACI 318-19. Several types of DIs (from single DIs to combined DIs based on parameters such as displacement, absorbed energy and stiffness) were calculated according to the experimental results. The results showed that the application of the higher strength steel expedited the failure process of the specimens. Moreover, the DIs indicated that the specimen fitted with HSS for both the longitudinal and transverse rebars had the greatest damage propagation speed of the frames. For the BCCs, the specimen with HSS as just the longitudinal rebars showed the greatest damage propagation speed. The results also showed that the displacement-based DIs were less accurate than the other types of DIs for studying the damage behaviour of both the frame and the BCC specimens. The combined DIs were found to be more accurate than the other DIs.