Abstract
This study investigated the multi-fiber pullout resistance of high-strength smooth steel fibers embedded in ultra-high-performance concrete (UHPC) at different loading rates. To discover the source of the fiber group effect on fiber pullout resistance, multi-fiber pullout tests were employed by changing the number of fibers, fiber-to-fiber distance, and difference in embedded lengths. The main source of the fiber group effect was found to be the reduced contact pressure per fiber, in the specimens containing more fibers, generated by matrix shrinkage: the fiber pullout stress at the static loading rate (0.0167 mm/s) decreased from 786.58 to 618.59 MPa (21.4 % reduction) as the number of fibers increased from 1 to 25. The equivalent bond strength of smooth steel fiber in UHPC generally increased from 4.5–5.2 to 5.9–7.1 MPa as the loading rate increased from 0.0167 to 1.67 mm/s. The favorable rate-sensitive pullout resistance of multi-fiber pullout specimens was notably affected by the number of fibers and fiber distance: the specimens containing nine fibers with a 2.7 mm fiber distance produced the highest dynamic increase factor (1.37) owing to enhanced interactions between interfacial cracks.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
