Bond Stress Analysis Between High-Performance Steel Fiber Reinforced Mortar and Deformed Steel Bars Under Pull-Out Test

Despite increased utilization of high-performance mortars in construction, there remains a paucity of research concerning the bond performance of steel reinforcement, particularly within masonry structures. This study characterizes the bond stress behavior in high-performance steel fiber mortar (HPSFRM) to define critical design bond stress parameters. Pull-out tests were performed, incorporating three primary variables: compressive resistance, steel fiber volume, and steel rebars diameter. To support safe and reliable bond design in HPSFRM precast members, various methods for analyzing bond strength, alongside empirical predictive equations, were evaluated. The results revealed that although the rate of increase in bond strength was impacted by the incorporation of steel fibers, the bond strength demonstrated significant improvement in the mortar compressive strength. Introducing steel fibers at a volumetric content of 1% doubled the bond strength. The optimum fiber content was found at 1%, where bond strength increased by 6% and slip by 102% due to effective fiber bridging. Increasing the dosage to 2% yielded only a marginal 2–5% gain, hindered by clustering and poor dispersion. Variations in steel bar diameter had a more pronounced effect on bond stress behavior. The proposed model addresses the underestimation of bond strength and ductility by existing empirical models and code provisions.