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桥梁结构刚度随损伤发展会逐渐发生不可逆的退化,刚度退化与疲劳损伤之间有一定的内在关联,通过疲劳试验研究了刚度退化的规律和计算方法。疲劳试验发现钢筋混凝土空心板梁的刚度呈现出明显的三阶段退化规律:在0~0.15Nf阶段,梁的挠度增长非常明显,甚至可以达到疲劳破坏时总挠度的40%,但挠度增长速率逐渐变小;在0.15Nf~0.90Nf阶段,梁的挠度增长速率逐渐变小直至接近某一较小的常数;在0.90Nf~Nf阶段,梁的挠度增长速率逐渐变大,开始进入脆性疲劳断裂阶段,试验梁很快疲劳破坏。刚度退化曲线符合S形形态。根据刚度退化规律对试验数据进行拟合,得到可用于计算钢筋混凝土空心板梁刚度退化程度的公式,该公式与5根试验梁的试验结果吻合度较好,能够实现对刚度退化的定量描述。
The stiffness of the bridge structure will gradually irreversibly degrade with the development of the damage. There is a certain intrinsic relationship between the stiffness degradation and fatigue damage. The fatigue degradation of the bridge is studied by the fatigue test. The fatigue test shows that the stiffness of reinforced concrete hollow slab beam shows obvious three-stage degeneracy. At 0 ~ 0.15Nf stage, the deflection of the beam increases obviously, even up to 40% of the total deflection under fatigue failure, but the deflection growth rate gradually increases And the deflection growth rate of the beam gradually decreases until reaching a smaller constant at 0.15Nf ~ 0.90Nf. At the stage of 0.90Nf ~ Nf, the deflection growth rate of the beam gradually becomes larger and begins to enter the stage of brittle fatigue fracture , Test beam quickly fatigue damage. Stiffness degradation curve in line with the S-shaped morphology. According to the law of stiffness degradation, the experimental data are fitted to obtain the formula that can be used to calculate the stiffness degradation of the reinforced concrete hollow slab. The formula is in good agreement with the experimental results of the five test beams and can quantitatively describe the stiffness degradation.