Liu Jingya, Huo Jingsi, Wang Haitao, Tang Zhongping, Zhang Qingyan, Yi Shixiang
Institute of Structural Material Failure and Strengthening Technology, Ningbo Polytechnic, Ningbo 315800, China.
Fujian Provincial Key Laboratory of Intelligent Infrastructure and Monitoring, Huaqiao University, Xiamen 361021, China.
Materials (Basel). 2024 Apr 28;17(9):2076. doi: 10.3390/ma17092076.
Impact tests on post-fire concrete confined by Carbon Fiber-Reinforced Polymer/Plastic (CFRP) sheets were carried out by using Split Hopkinson Pressure Bar (SHPB) experimental setup in this paper, with emphasis on the effect of exposed temperatures, CFRP layers and impact velocities. Firstly, according to the measured stress-strain curves, the effects of experiment parameters on concrete dynamic mechanical performance such as compressive strength, ultimate strain and energy absorption are discussed in details. Additionally, temperature caused a softening effect on the compressive strength of concrete specimens, while CFRP confinement and strain rate play a hardening effect, which can lead to the increase in dynamic compressive strength by 1.8 to 3.6 times compared to static conditions. However, their hardening mechanisms and action stages are extremely different. Finally, nine widely accepted Dynamic Increase Factor (DIF) models considering strain rate effect were summarized, and a simplified model evaluating dynamic compressive strength of post-fire concrete confined by CFRP sheets was proposed, which can provide evidence for engineering emergency repair after fire accidents.
本文采用分离式霍普金森压杆（SHPB）试验装置对火灾后碳纤维增强聚合物/塑料（CFRP）布约束混凝土进行了冲击试验，重点研究了暴露温度、CFRP层数和冲击速度的影响。首先，根据测得的应力-应变曲线，详细讨论了试验参数对混凝土动态力学性能（如抗压强度、极限应变和能量吸收）的影响。此外，温度对混凝土试件的抗压强度有软化作用，而CFRP约束和应变率则起硬化作用，与静态条件相比，这可使动态抗压强度提高1.8至3.6倍。然而，它们的硬化机制和作用阶段却截然不同。最后，总结了9种广泛认可的考虑应变率效应的动力增加系数（DIF）模型，并提出了一种评估火灾后CFRP布约束混凝土动态抗压强度的简化模型，可为火灾事故后的工程应急修复提供依据。
