A novel type of fiber, the double-helix macro BFRP (Basalt Fiber Reinforced Polymer) fiber, has been proposed to effectively increase the cracking, tensile strength, and ductility of concrete. BFRP material offers high tensile strength, good corrosion resistance, and low costs, while the double-helix geometry provides excellent bond-slip performance for the fiber and concrete matrix. This study conducted a series of three-point bending tests to measure the fracture energy of concrete reinforced with double-helix BFRP fibers and analyzed the influences of fiber orientation (aligned fibers and random fibers) on cracking loads, peak loads, flexural strengths, and fracture energy. The test results revealed a significant improvement in the fracture energy of concrete reinforced with double-helix macro BFRP fibers, with aligned fibers showing a 26.4% higher fracture energy compared to random fibers. Additionally, the flexural strength of concrete reinforced with aligned fibers increased by 29.7% compared to random fibers. Finite element models of the three-point bending tests were established using LS-DYNA software, and the concrete model developed by Karagozian & Case, Inc.(K&C) was calibrated based on the fracture energy results to obtain the material model of the fiber-reinforced concrete considering fiber orientation. The errors between the simulated and tested maximum load values for three-point bending tests of plain concrete, FRC, and FRCSS were 8.3%, 4.0%, and 11.4%, respectively, which indicates that the simulation results were found to be in good agreement with the test results. This study provides theoretical foundations and technical support for the practical engineering applications of double-helix BFRP fibers.

中文翻译：

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双螺旋宏观BFRP纤维混凝土断裂能的试验与数值研究

人们提出了一种新型纤维——双螺旋宏观BFRP（玄武岩纤维增强聚合物）纤维，可以有效提高混凝土的抗裂性、抗拉强度和延展性。 BFRP 材料具有高拉伸强度、良好的耐腐蚀性和低成本，而双螺旋几何形状为纤维和混凝土基体提供了优异的粘结滑移性能。本研究进行了一系列三点弯曲试验来测量双螺旋 BFRP 纤维增强混凝土的断裂能，并分析了纤维取向（排列纤维和随机纤维）对开裂荷载、峰值荷载、弯曲强度和断裂能。测试结果显示，双螺旋粗 BFRP 纤维增强混凝土的断裂能得到显着改善，与随机纤维相比，排列纤维的断裂能高出 26.4%。此外，与随机纤维相比，用排列纤维增强的混凝土的弯曲强度提高了29.7%。利用LS-DYNA软件建立了三点弯曲试验的有限元模型，并根据断裂能结果对Karagozian & Case, Inc.(K&C)开发的具体模型进行了校准，得到了纤维的材料模型。考虑纤维取向的钢筋混凝土。普通混凝土、FRC 和 FRCSS 的三点弯曲试验的模拟最大荷载值与测试最大荷载值之间的误差分别为 8.3%、4.0% 和 11.4%，这表明模拟结果吻合良好。与测试结果。该研究为双螺旋BFRP纤维的实际工程应用提供理论基础和技术支撑。