Local compression capacity of steel fiber reinforced ultra-high performance concrete containing coarse aggregate

Abstract

Steel fiber reinforced ultra-high performance concrete containing coarse aggregate (CA-UHPFRC) can significantly reduce cost and shrinkage compared to conventional ultra-high performance concrete (UHPC). The application of CA-UHPFRC to prestressed concrete structures is a novel exploration. However, the existing prediction models are generally suitable for ordinary-strength concrete, which may generate a large error when applied to UHPC because of the insufficient consideration of the effects on concrete strength and ducts. To explore the anchorage zone mechanism and fill the blank of local bearing capacity calculation method in prestressed CA-UHPFRC structures, 22 specimens were tested. The failure characteristics, crack patterns and the relationships between load versus deformation were discussed. The results indicated that CA-UHPFRC exhibited ductile failure modes under local pressure, where the ratios of cracking load to ultimate load ranged from 57.2 % to 84.1 %. The wedge cleaving theory was still followed by CA-UHPFRC, and the integrity and fine post-peak performance can be maintained. Besides, the effects of concrete strength, local area aspect ratio and duct diameter were fully discussed. Finally, prediction equations were developed and experimentally verified, which comprehensively considered the multiple factors. This research provided a novel insight into the accurate bearing capacity calculation methods for CA-UHPFRC in anchorage zones.