This paper presents an experimental investigation on the stress–strain behavior and the damage mechanism of polypropylene fiber reinforced concrete (PFRC) under monotonic and cyclic compression. Fifty-four specimens for different fiber volume fractions and aspect ratios were tested. Acoustic emission (AE) technique was used to monitor the damage progression. The damage mechanism of concrete was analyzed based on the AE parametric analysis. The results show that the incorporation of polypropylene fiber (PF) has a positive effect on the monotonic and cyclic behaviors of concrete, especially for the post-cracking branch. The toughness and ultimate strain are enhanced and the performance degradation in terms of elastic stiffness and strength is alleviated by the addition of PF. However, PF has little influences on the plastic strain, and the damage process of concrete is mainly driven by the envelope strain. The effect of fiber volume fraction on the cyclic behavior of concrete shows more pronounced than that of aspect ratio. In addition, it is found from AE results that the damage, closely related to AE events, has a quick evolution just after the peak stress, with the AE hits having a concentrated release. The total amount of AE hits increases with increasing fiber volume fraction due to fiber pullout and sliding, while the concrete with fiber aspect ratio of 280 reaches the largest amount. Meanwhile, as substantiated by AE, the failure of PFRC shows an obvious shear mode, with shear cracks dominating the damage progression. Finally, a damage elasto-plastic model is developed to predict the monotonic and cyclic responses of PFRC and the prediction yields a fairly close estimation with experimental results.

中文翻译：

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聚丙烯纤维混凝土受压损伤行为试验研究

本文对聚丙烯纤维混凝土 (PFRC) 在单调和循环压缩下的应力-应变行为和损伤机制进行了实验研究。测试了 54 个不同纤维体积分数和纵横比的试样。声发射 (AE) 技术用于监测损伤进展。基于AE参数分析，分析了混凝土的损伤机理。结果表明，聚丙烯纤维（PF）的掺入对混凝土的单调和循环行为具有积极影响，特别是对后开裂分支。通过添加PF，韧性和极限应变得到增强，弹性刚度和强度方面的性能下降得到缓解。然而，PF对塑性应变的影响很小，混凝土的破坏过程主要由包络应变驱动。纤维体积分数对混凝土循环行为的影响比纵横比更显着。此外，从声发射结果发现，与声发射事件密切相关的损伤在峰值应力后迅速演化，声发射击中具有集中释放。由于纤维拉出和滑动，AE撞击总量随着纤维体积分数的增加而增加，而纤维纵横比为280的混凝土达到最大。同时，正如 AE 所证实的那样，PFRC 的失效显示出明显的剪切模式，剪切裂纹主导了损伤进程。最后，