The fatigue behavior of a reinforced UHPFRC (Ultra High Performance Fiber Reinforced Cementitious composite) T-shaped beam under four-point bending is investigated. The beam was subjected to a fatigue loading range equal to 49% of the static resistance and failed after 0.88 million cycles. It was instrumented with extensometers, strain gauges and distributed fiber optic sensors for strain monitoring. The fatigue process consists of three stages: with rapid, stable and again rapid growth of strains during 10%, 80% and 10% of total number of fatigue cycles, respectively. Except of the first 10%, this process takes place locally; therefore, it cannot be followed with the deflection measurement. During the stable stage, growth of strain occurs at minimum loading level in the fatigue cycle, indicating a fatigue damage process under tensile-compressive response of UHPFRC. Advanced fatigue crack propagation in the reinforcement bar determines the location of rupture of the beam. When the remaining cross-section of the rebar does not suffice to carry the tensile load, stress is transmitted to the encompassing UHPFRC causing its fast deterioration. Complete rupture of the rebar occurs only at the end of the test, when the beam collapses.

研究了增强型 UHPFRC（超高性能纤维增强水泥基复合材料）T 形梁在四点弯曲下的疲劳行为。梁承受的疲劳载荷范围等于静态阻力的 49%，并在 88 万次循环后失效。它配备了引伸计、应变仪和分布式光纤传感器，用于应变监测。疲劳过程包括三个阶段：分别在疲劳循环总数的 10%、80% 和 10% 期间应变快速、稳定和再次快速增长。除了前 10%，这个过程在本地进行；因此，不能进行挠度测量。在稳定阶段，应变增长发生在疲劳循环中的最小载荷水平，表明在 UHPFRC 拉伸 - 压缩响应下的疲劳损伤过程。钢筋中的高级疲劳裂纹扩展决定了梁的断裂位置。当钢筋的剩余横截面不足以承受拉伸载荷时，应力会传递到包围的 UHPFRC，导致其快速劣化。钢筋完全断裂仅在测试结束时发生，此时梁会坍塌。