This paper presents a sectional analysis of cracked fiber reinforced concrete (FRC) under flexural loading. The approach considers three separate loading conditions: monotonic, cyclic, and creep bending loads. Different parts of the approach are experimentally calibrated and validated with tests on polypropylene FRC. In the monotonic regime, numerical optimization is used to find the optimal stress–strain relation of FRC to capture the experimental bending behavior as closely as possible, while satisfying the horizontal force and bending moment equilibrium. To model the cyclic behavior, the constitutive law is extended by introducing a tension-only scalar damage function. The agreement between the predicted and measured response is again very good, and the measured upwards shift of the neutral axis during unloading is predicted as well. Finally, the flexural creep response of a cracked FRC beam is simulated by using uniaxial creep data. The approach predicts the time-dependent crack widening under sustained flexural loading and can be used to check SLS criteria in the design of FRC elements.

中文翻译：

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开裂纤维增强混凝土弯曲徐变截面分析

本文介绍了在弯曲载荷下开裂的纤维增强混凝土 (FRC) 的截面分析。该方法考虑了三种单独的载荷条件：单调载荷、循环载荷和蠕变弯曲载荷。该方法的不同部分通过对聚丙烯 FRC 的测试进行了实验校准和验证。在单调状态下，数值优化用于找到 FRC 的最佳应力-应变关系，以尽可能接近地捕捉实验弯曲行为，同时满足水平力和弯矩平衡。为了模拟循环行为，本构律通过引入仅张力标量损伤函数进行了扩展。预测响应和测量响应之间的一致性再次非常好，并且还预测了卸载期间测量的中性轴向上移动。最后，使用单轴蠕变数据模拟开裂 FRC 梁的弯曲蠕变响应。该方法可预测持续弯曲载荷下随时间变化的裂纹加宽，并可用于检查 FRC 元件设计中的 SLS 标准。