Investigation of the pullout behavior of multiple steel fibers embedded in concrete

Abstract

This study evaluates the pullout behavior of multiple steel fibers in concrete through pullout tests with fiber quantities of 1, 4, and 16. The specimens were prepared to clarify the influence of fiber number on bond strength, stress transfer mechanisms, and crack development at the fiber-concrete interface. The results indicate that as the number of fibers increases, the average bond strength per fiber tends to decrease, primarily due to the redistribution of interfacial stresses and the overlapping of neighboring cracks. In particular, the single-fiber specimen exhibited the highest pullout resistance per unit fiber, whereas specimens with multiple fibers exhibited a significant reduction. Nevertheless, increasing the number of fibers enhanced the overall energy dissipation capacity, attributed to more complex crack interactions. The findings provide valuable experimental evidence for characterizing the bond mechanism of steel fibers in concrete and support the optimal design of fiber-reinforced concrete for practical structural applications.