Effects of inclination angle on pullout performance of hooked end fiber embedded in UHPC

Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) is a material with superior mechanical strength and energy absorption capacity. The orientation of the fiber and the fiber-matrix bond relationship are important factors that affect the performance of UHPFRC. In this study, the pullout performances of hooked end fibers embedded in ultra-high performance concrete (UHPC) matrix under various inclination angles are investigated. It is shown that for the tested fiber and UHPC matrix, the optimum angle for reaching the maximum pullout energy is around 10 degrees; when the inclination angle further increases fiber rupture and matrix spalling occur more frequently. Results from this study can contribute to a better understanding and utilization of fibers effects in UHPFRC