This paper presents the behavior of the interfacial bond between an innovative FRP fibre and cement mortar under time-dependent loading. Two types of FRP fibres—GFRP and CFRP were investigated. Particularly, the fibre pullout response under quasi-static loading is compared with the response under dynamic loading. To gauge the long term behavior of cracked fibre reinforced composites, fibre relaxation tests were conducted in which initial strain was imparted and sustained, and the relaxation of the composite in terms of drop in load over time period was monitored at room temperature as well as at 50 °C. FRP fibres were found to be to some extent sensitive to loading rate, with an increase in the range of 30–50% in the peak load under dynamic loading. The GFRP fibres itself depicted higher strengths under dynamic loading rate. Under a sustained fibre slip, FRP fibres showed a lower relaxation at both room temperature and at 50 °C compared to commercially available steel and polypropylene fibres. There was also no conclusive change in pullout response in specimen subjected to sustained strains compared to reference.

中文翻译：

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时变载荷下 FRP 纤维-水泥基体界面结合

本文介绍了新型 FRP 纤维和水泥砂浆在时变载荷下的界面结合行为。研究了两种类型的 FRP 纤维——GFRP 和 CFRP。特别地，将准静态加载下的纤维拉拔响应与动态加载下的响应进行了比较。为了测量开裂的纤维增强复合材料的长期行为，进行了纤维松弛试验，其中施加并维持初始应变，并在室温和50℃。发现 FRP 纤维在一定程度上对加载速率敏感，在动态加载下峰值载荷增加 30-50%。GFRP 纤维本身在动态加载速率下表现出更高的强度。在持续的纤维滑移下，与市售的钢和聚丙烯纤维相比，FRP 纤维在室温和 50°C 下均表现出较低的松弛。与参考相比，承受持续应变的样品的拔出响应也没有决定性的变化。