
科学技术与工程

中国技术经济学会
Experiment of the Bond Behavior between Steel-PVA Hybrid Fiber High Performance Concrete and Deformed Bars after Elevated Temperature
Cheng-xiang XU , Hong-jie LÜ , Qi-qi XU , Hong-bing ZHU
Science Technology and Engineering ›› 2024, Vol. 24 ›› Issue (20) : 8615 -8623.
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, 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 cedompleted. Results show that the bonding failure modes of all groups of HFHPC specimens after high temperature are rebar pullout damage. Within the test temperature range, the volume fraction of steel fiber plays the most important role in bond strength, follows by mineral powder dosage, whereas the PVA fiber volume fraction has the minimum effect. With the increase of temperature, the bond strength of HFHPC specimens gradually decreases. Compared to the concrete specimens without fibers doping, the bond strength and peak slip of HFHPC specimens are increased under the same temperature conditions. The bond strength of HFHPC specimens is most significantly increased at 200 ℃, which is 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.
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