Shear performance of centrifugal forming hollow circular SFRC piles: Feasibility study of replacing stirrups with steel fibers

This paper aims to investigate shear performance and develop an equation for shear strength assessment of centrifugal forming hollow circular steel fiber reinforced concrete (HSFRC) piles in a practical manufacturing condition. The centrifugal forming was optimized using concrete mixes with different steel fibers. The shear performance and size effect of HSFRC and conventional hollow circular reinforced concrete (HRC) piles with/without stirrups were investigated. Results of X-ray visualization show that, after centrifugal forming, steel fibers were evenly distributed and reoriented in the circumferential direction of the piles, effectively enhancing shear performance. Even with a low steel fiber content of 0.5%, HSFRC piles achieve equivalent shear performance and less brittle behavior compared to HRC piles with shear reinforcement ratios of 0.27%. This implies that higher steel fiber contents can potentially be used to replace stirrups for a flexural failure. SFRC remarkably inhibited the size effect of HSFRC piles. Moreover, a proposed equation considering fiber orientation can better predict the shear strength of centrifugal forming HSFRC piles compared to existing equations.