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本文针对预应力混凝土桥梁工程中遇到的拉-压疲劳状态,进行了76个混凝土试件在等幅重复荷载作用下的轴拉、拉-压疲劳试验。在试验基础上,分析了混凝土抗拉、拉-压疲劳强度、刚度、变形的变化规律,给出了相应的S-N方程及古德曼图,并将本文试验结果同其它文献结果及有关规范作了比较。结果表明,混凝土轴心拉-压疲劳强度比轴拉疲劳强度显著降低。根据试验结果,建立了纵向总应变、弹性模量的经验公式,及其第二阶段总应变增长率、弹性模量衰减率分别与疲劳寿命的关系式。本文的研究结果,为预应力混凝土桥梁的设计、分析提供了依据。
In this paper, the tension-compression fatigue test of 76 concrete specimens subjected to constant amplitude and repeated load is carried out in view of the tension-compression fatigue conditions encountered in the prestressed concrete bridge engineering. On the basis of the experiment, the change rules of tensile, tensile and compression fatigue strength, stiffness and deformation of concrete are analyzed. The corresponding SN equation and the Goodman diagram are given. The results of this paper are compared with the results of other literatures and related specifications A The results show that the axial tensile-compression fatigue strength of concrete is significantly lower than the fatigue strength of axial compression. According to the experimental results, the empirical formula of the total longitudinal strain and elastic modulus in the longitudinal direction and the relationship between the total strain growth rate and the elastic modulus attenuation rate in the second stage and the fatigue life are established. The results of this paper provide the basis for the design and analysis of prestressed concrete bridges.