The use of fibers in reinforced concrete (RC) beams mainly improves both the bearing capacity and the cracking control. In this way, positive effects on the service life of RC structures can be expected. In this paper, the fiber influence on the flexural behavior of RC beams with different longitudinal reinforcement ratios (0.5% ≤ ρ_s ≤ 1.2%) is analyzed by testing small‐scale RC beams. Concretes incorporating 0, 25 and 50 kg/m³ of steel, 6 and 12 kg/m³ of glass macrofibers, and 5 and 10 kg/m³ of polymer macrofibers were studied. Crack and deflection control, as well as bearing capacity and crack localization were evaluated for a broad range of fiber‐reinforced concrete (FRC) toughness. It is verified that fibers, in the longitudinal reinforcement ratio considered, improve the bending behavior at serviceability limit state (SLS) and ultimate limit state (ULS) of RC beams, without limiting the structure ductility. It was also confirmed the philosophy of the fib Model Code 2010, such that FRC can be considered as a composite material where performance parameters govern its mechanical behavior. Finally, the several data available allowed to deeply analyze fib Model Code 2010 formulations (mean crack spacing and flexural bearing capacity) and to propose modifications where needed.

中文翻译：

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评估纤维对不同纵向配筋比的钢筋混凝土梁抗弯性能的影响

在钢筋混凝土（RC）梁中使用纤维主要提高了承载能力和裂缝控制能力。这样，可以预期对RC结构的使用寿命产生积极影响。在本文中，在RC的抗弯性能的纤维束的影响用不同的纵向加强比（0.5％≤  ρ_小号 ≤1.2％）是通过测试小型RC梁进行分析。掺入0、25和50 kg / m ³的钢，6和12 kg / m ³的玻璃大纤维以及5和10 kg / m ^3的混凝土研究了聚合物大纤维的制备。针对广泛范围的纤维增强混凝土（FRC）韧性，评估了裂纹和挠度控制以及承载能力和裂纹局部性。可以证明，在考虑纵向增强比的情况下，纤维可以改善RC梁在使用极限状态（SLS）和极限极限状态（ULS）时的弯曲性能，而不会限制结构的延展性。还确认了fib模型代码2010的原理，因此FRC可以被认为是一种复合材料，其中性能参数决定了其机械性能。最后，一些可用数据可以深入分析fib 模型代码2010公式（平均裂缝间距和抗弯承载力），并在需要时提出修改建议。