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<p>This study introduces an innovative approach to improve the fire resistance of reinforced concrete (RC) structures based on the heat-induced prestress of iron-based shape memory alloys (Fe-SMA). The Fe-SMA embedded in concrete can automatically activate its shape memory effect under fire to generate tensile stress called recovery stress to apply prestress to the parent structure. The process of generating recovery stress is also called self-prestressing. The Fe-SMA can enable traditional concrete structures to respond to fire actively and automatically through the self-prestressing effect, improving the fire resistance of the RC structures. Fire tests were performed to examine the fire resistance of concrete beams hybrid reinforced with steel and Fe-SMA rebars. The recovery stress reduces beam deflection under fire while increasing the fire resistance. The fire resistance of the beams in which 2 and 4 of the 6 longitudinal reinforcements were replaced with Fe-SMA bars increased from 112 to 141&#xa0;min and 152&#xa0;min, respectively, when compared to the control beam. In addition, the deflection rate of the hybrid reinforced beam is also decreased. The residual deflection of hybrid reinforced beams does not increase when cooled to room temperature. With the reasonable arrangement of Fe-SMA rebar, the recovery stress can last throughout the fire exposure time to improve the fire resistance of concrete structures.</p>

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A Novel Approach of Improving the Fire Resistance of RC Structures Based on the Heat-Induced Prestress of Fe-SMA

  • 期刊论文

  • 发表日期：

    2025年7月10日

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  • Yichuan Zheng,
  • Chushi Cui,
  • Zhiqiang Dong,
  • Hong Zhu,
  • Yihua Zeng,
  • Yu Sun

摘要

This study introduces an innovative approach to improve the fire resistance of reinforced concrete (RC) structures based on the heat-induced prestress of iron-based shape memory alloys (Fe-SMA). The Fe-SMA embedded in concrete can automatically activate its shape memory effect under fire to generate tensile stress called recovery stress to apply prestress to the parent structure. The process of generating recovery stress is also called self-prestressing. The Fe-SMA can enable traditional concrete structures to respond to fire actively and automatically through the self-prestressing effect, improving the fire resistance of the RC structures. Fire tests were performed to examine the fire resistance of concrete beams hybrid reinforced with steel and Fe-SMA rebars. The recovery stress reduces beam deflection under fire while increasing the fire resistance. The fire resistance of the beams in which 2 and 4 of the 6 longitudinal reinforcements were replaced with Fe-SMA bars increased from 112 to 141 min and 152 min, respectively, when compared to the control beam. In addition, the deflection rate of the hybrid reinforced beam is also decreased. The residual deflection of hybrid reinforced beams does not increase when cooled to room temperature. With the reasonable arrangement of Fe-SMA rebar, the recovery stress can last throughout the fire exposure time to improve the fire resistance of concrete structures.