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通过跨座式单轨交通PC轨道梁正截面弯曲及梁端剪切疲劳试验,研究混凝土应力、跨中挠度、刚度降低系数以及梁体基频、阻尼系数等动力特性与疲劳循环次数的关系。研究表明,梁体结构在经历300万次双向弯曲和剪切疲劳加载作用后,结构应力、位移重复性良好,梁体具有较好的耐疲劳性能;最大疲劳荷载等级作用下受压区混凝土应力幅较低,一般不会发生疲劳破坏,荷载重复300万次后梁体刚度有一定退化趋势;梁体基频、阻尼系数等动力特性随疲劳加载次数增加均有所降低,但在100万次疲劳加载后基本趋于稳定。
Through the cross-section bending test and the shear fatigue test of the beam on the monorail track, the relationship between the dynamic characteristics such as concrete stress, midspan deflection, stiffness reduction coefficient, base frequency and damping coefficient of the beam and fatigue cycles is studied. The results show that the structure of the beam body has good repeatability of stress and displacement after being subjected to three million times of bending and shearing fatigue loading, and the beam body has good fatigue resistance. Under the condition of the maximum fatigue load level, the stress of the concrete in the compressive zone Generally, no fatigue damage occurs. The stiffness of the beam body will degenerate after 300 million repetitions. The dynamic characteristics such as the fundamental frequency and the damping coefficient of the beam body decrease with the increase of the fatigue loading frequency. However, after 1 million fatigue loads The basic trend stabilized.