Abstract:In order to research the effects of elevated temperatures on bond behavior between steel-Polyvinyl Alcohols (PVA) hybrid fiber high performance (HFHPC) concrete and deformed reinforcement. With 200℃, 400℃, 600℃ and 800℃ as the target temperatures,25 sets of HFHPC specimens were designed by selecting volume fraction of steel fiber and PVA fiber and dosing of mineral powder as the orthogonal test factors. The central pull-out test under monotonic loading was completed. Results of orthogonal experiment showed that the bonding failure modes of all groups of HFHPC specimens after high temperature were rebar pullout damage. Within the test temperature range, the volume fraction of steel fiber played the most important role in bond strength, followed by mineral powder dosage, whereas the PVA fiber volume fraction had the minimum effect. With the increase of temperature, the bond strength of HFHPC specimens gradually decreased. Compared to the concrete specimens without fibers doping, the bond strength and peak slip of HFHPC specimens were increased under the same temperature conditions. The bond strength of HFHPC specimens was most significantly increased at 200°C, which was increased by 33.69%, 35.76%, 37.54%, and 46.03%, respectively. The hybrid fibers significantly improve the peak interfacial energy between high performance concrete and steel reinforcement after high temperatures, significantly improve the bond ductility and energy dissipation capacity. The proposed bond-slip curves of hybrid fiber concrete and deformed reinforcement after considering the temperature effect are in good fit with the experimental measured results, which can provide a reference for the structural damage assessment of hybrid-fiber high-performance concrete and the reinforcement scheme after fire.