凝土轴心拉-压疲劳性能研究

Study on the Behavior of Concrete Under Axial Tension-Compression Fatig ue Loading

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。

The fatigue tests on axial tension an d tension-compression under consta nt amplitude cyclic loading have been carried out on plain concrete in this paper against the fatigue state of te nsion-compression in prestressed c oncrete bridges,and the test results are compared with those obtained by other researchers and code for design.The fatigue regularities of strength,stiffness,and deforma tion are analyzed based on the results of the experiment.The results of th e tests have been presented in the relationship o f S-N and Goodman diagrams.Test results s how that the fatigue strength of concrete under axial tension-compression is much lower than that under axial tension.Two expirical formulas for calc ulating the total longitudinal strain and the elastic modulus with respect to number of loading cycles and the relationsh ips of the incremental rate of the total strain and the decay rate of the elastic modu lus each with the fatigue life in the main stage,i.e.the second stage of the developm ent of strain,are given.The results of investigation in this paper furni sh the experimental basis for the design an d analysis of pre-stressed concrete bridges under cyclic loading.