超高韧性水泥基复合材料（UHTCC）压缩疲劳性能试验研究

发布时间：2018-04-16 03:20

本文选题：UHTCC + 压缩疲劳　；参考：《浙江大学》2015年硕士论文

【摘要】：混凝土是用量最大、用途最广的建筑材料,其疲劳失效问题研究对桥梁、道路、高层、海洋工程等都具有重要意义,以往多数研究结果表明,加入纤维有益于改善混凝土的抗疲劳性能。以微观力学和断裂力学为指导的UHTCC (Ultra High Toughness Cementitious Composites),具有超高的韧性和优异的裂缝控制能力。当前,国内外UHTCC疲劳研究主要集中在弯曲疲劳性能上,为了全面研究其疲劳性能,本文在静载实验的基础上,进行一系列等幅压缩疲劳实验,研究应力水平、频率对UHTCC压缩疲劳性能的影响。研究疲劳裂缝扩展、纤维破坏情况,发现压缩疲劳破坏断面可分为疲劳源区、过渡区和类静态破坏区。疲劳源区存在纤维较少等缺陷,最先开裂后因反复摩擦而呈“黑色”,断面上纤维因严重挤压而变形；类静态破坏区形成于试件疲劳失效前的极短时间内,所受应力较高,纤维拔出比例大、纤维完整性好。通过不同应力水平压缩疲劳实验,得到压缩S-N曲线,线性回归的压缩疲劳强度为0.688,与普通混凝土、钢纤维混凝土相比,处于较高水平。不同频率压缩疲劳实验表明,随着频率降低,疲劳寿命降低,但在一定的频率范围内(包含0.5Hz-2Hz),频率对压缩疲劳寿命影响较小。以往实验结果显示,普通混凝土和钢纤维混凝土的压缩疲劳破坏变形与静态曲线下降段相应应力水平处的变形相近,而本文实验结果表明,UHTCC压缩疲劳破坏变形明显大于静态曲线下降段相应应力水平处的变形。本文通过实验发现了UHTCC压缩疲劳破坏变形的特点,并探究了UHTCC压缩疲劳破坏过程和机理,所做工作对于建立UHTCC压缩疲劳模型,进而推动其工程应用,都具有重要意义。
[Abstract]:Concrete is the most widely used building material. The research on fatigue failure of concrete is of great significance to bridges, roads, high-rise buildings, ocean engineering, etc.The addition of fiber is beneficial to improve the fatigue resistance of concrete.UHTCC Ultra High Toughness Cementitious compositions, which is guided by micromechanics and fracture mechanics, has high toughness and excellent fracture control ability.At present, the domestic and foreign UHTCC fatigue research is mainly focused on the bending fatigue performance. In order to study its fatigue performance comprehensively, a series of constant amplitude compression fatigue experiments are carried out on the basis of static load experiments to study the stress level.The effect of frequency on the compressive fatigue properties of UHTCC.The fatigue crack propagation and fiber failure are studied. It is found that the compressive fatigue failure section can be divided into fatigue source region, transition zone and quasi-static failure zone.There are some defects in the fatigue source area, such as less fiber, "black" after cracking and repeated friction, and deformation of the fiber on the section due to severe compression. The quasi-static failure zone is formed in the very short time before fatigue failure of the specimen, and the stress is relatively high.Fiber pullout ratio is large, fiber integrity is good.The compression S-N curve was obtained by the compression fatigue experiments of different stress levels. The compressive fatigue strength of linear regression is 0.688, which is higher than that of ordinary concrete and steel fiber reinforced concrete (SFRC).Different frequency compression fatigue experiments show that the fatigue life decreases with the decrease of frequency, but in a certain frequency range (including 0.5Hz-2Hz), the frequency has little effect on the compressive fatigue life.The experimental results show that the compressive fatigue failure deformation of ordinary concrete and steel fiber reinforced concrete is similar to that of the corresponding stress level in the descending section of the static curve.The experimental results show that the compressive fatigue failure deformation of UHTCC is obviously larger than that of the corresponding stress level in the descending section of the static curve.In this paper, the characteristics of UHTCC compression fatigue failure deformation are found through experiments, and the process and mechanism of UHTCC compression fatigue failure are explored. The work done is of great significance for the establishment of UHTCC compression fatigue model and the promotion of its engineering application.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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