冻融损伤混凝土单调及重复荷载下应力—应变关系试验研究

发布时间：2018-10-23 15:25

【摘要】：冻融损伤已成为混凝土结构耐久性研究的重要课题之一。我国很多地区冬季气候严寒，加之混凝土结构在安全使用期内常遭受单调或重复加卸载作用，因此本文对冻融损伤混凝土单调及重复荷载作用下的应力应变关系进行研究，为混凝土结构抗震性能评估提供基础数据，对混凝土结构防灾减灾具有重要的理论研究价值。本文对混凝土棱柱体试块进行最高次数为400次的冻融循环试验，并测量试块的质量及动弹性模量，建立质量损失率、相对动弹性模量与冻融循环次数之间的关系式；对冻融次数分别为0、100、200、300、400次的五组试块进行等应变速率的单调和重复加载试验，分析其破坏形态，，对比研究了单调与重复加载破坏形态的差异，并分别得出了单调与重复荷载下的峰值应力、峰值应变与冻融循环次数间的关系式，得到不同冻融循环次数后混凝土的应力应变全曲线。针对五组单调与重复加载的应力应变全曲线试验结果进行了深入的分析：首先，采用matlab软件对单调荷载作用下应力应变曲线的上升段和下降段进行拟合，得出上升段的参数a和下降段的参数b，建立二者与冻融次数N的关系；其次，对重复荷载作用下的卸载曲线进行拟合，得到卸载参数n，采用以n=1+0.7ε u/εp为原型修改参数值的公式n=1+sε u/εp得出参数s，并建立了参数s与冻融循环次数N之间的关系方程；最后，对重复荷载作用下的再加载曲线进行拟合，得到再加载参数n、α在不同冻融循环次数下的分布规律。
[Abstract]:Freeze-thaw damage has become one of the most important research topics in the durability of concrete structures. In many areas of China, the winter climate is severe, and concrete structures are often subjected to monotone or repeated loading and unloading in the safe life. Therefore, the stress strain relationship of freeze-thaw damaged concrete under monotone and repeated loads is studied in this paper. It provides basic data for seismic performance evaluation of concrete structures and has important theoretical research value for the prevention and mitigation of concrete structures. In this paper, the maximum number of freeze-thaw test of concrete prism is 400 times, and the mass and dynamic elastic modulus of concrete prism are measured, and the relationship between mass loss rate, relative dynamic elastic modulus and freeze-thaw cycle times is established. Five groups of specimens with freezing and thawing times of 0 100 200 300 400 times were subjected to monotone and repeated loading tests with equal strain rate. The failure patterns were analyzed and the difference between monotone and repeated loading failure patterns was compared. The relationship between peak stress, peak strain and freeze-thaw cycle times under monotone and repeated loads is obtained, and the full stress-strain curves of concrete under different freeze-thaw cycles are obtained. The experimental results of five groups of stress-strain curves under monotone and repeated loading are analyzed. Firstly, the ascending and descending sections of the stress-strain curves under monotone loading are fitted by matlab software. The relation between the parameters a of rising section and the parameter of descending section b and the number of freeze-thaw times N is established. Secondly, the unloading curve under repeated load is fitted. The unloading parameter (n) is obtained. The formula of nnn1s 蔚 u / 蔚 p is used to modify the parameter value, and the relation equation between the parameter s and the number of freeze-thaw cycles N is established. Finally, the reloading curve under repeated load is fitted. The distribution of the reloading parameters n and 伪 under different freeze-thaw cycles was obtained.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU528.0

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