An experimental study on the behaviour of fibre reinforced concrete under flexure is presented, where pre-cracked notched beams were tested under cyclic loading for concrete with different dosages of hooked-ended steel fibres. The fatigue crack growth and stiffness degradation during the cycles are discussed in term of the rate of evolution of crack opening, and the critical crack opening is identified, beyond which the crack growth becomes unstable. S – N curves have been proposed with respect to the critical crack opening as these would be more relevant to design avoiding sudden failure. It is evident that higher dosages of fibres improve the fatigue life of cracked concrete only when the magnitudes of the cyclic loading are high, and that the effect of dosage is insignificant at lower magnitudes. For the fibre concretes considered here, the endurance limit seems to be about 50% of the pre-crack load in the post-peak regime.

中文翻译：

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纤维增强混凝土弯曲疲劳断裂

介绍了纤维增强混凝土在弯曲作用下的行为的实验研究，其中对具有不同剂量钩端钢纤维的混凝土在循环荷载下测试了预开裂缺口梁。循环期间的疲劳裂纹扩展和刚度退化根据裂纹扩展的演化速率进行讨论，并确定了临界裂纹扩展，超过临界裂纹扩展变得不稳定。已经针对临界裂纹张开提出了 S-N 曲线，因为这些曲线与避免突然失效的设计更相关。很明显，只有当循环载荷的大小较高时，较高的纤维剂量才能提高开裂混凝土的疲劳寿命，而在较低的强度下，剂量的影响不显着。对于这里考虑的纤维混凝土，