为研究混凝土在破坏过程中的能量演化规律,对混凝土试件在不同侧应力(0,0.1fc,0.3fc,0.5fc)、不同应变速率(10-5/s,10-4/s,10-3/s,10-2/s)下进行循环加-卸载试验,得到单轴压缩下输入总能量、弹性能和耗散能随应变增长的演化和分配规律。试验结果表明:在整个加载阶段,应变速率为10-5/s及10-4/s时,混凝土输入总能量、弹性能、耗散能都随应变的增大而先增大后减小;应变速率为10-3/s及10-2/s时,混凝土输入总能量、弹性能、耗散能都随应变的增加而逐渐增加;在相同侧应力下,应变速率增大,混凝土在破坏时积聚的能量和混凝土的储能会增加;混凝土达到储能极限时弹性能比例最小为30%,而最大为58%;在应变速率相同时,混凝土的储能极限随着侧应力的增大而增大,侧应力会抑制裂缝的发展;在侧应力为(0.1,0.3)fc时,混凝土的弹性能密度随侧应力增大呈线性增大。研究成果有助于研究人员了解混凝土的破坏过程。
Abstract
Cyclic loading and unloading tests were performed on concrete specimens under different lateral stresses (0, 0.1fc, 0.3fc, 0.5fc) and strain rates (10-5/s, 10-4/s, 10-3/s, 10-2/s), respectively, to investigate the energy evolution of concrete in failure process. The evolution and distribution of total energy input, accumulated elastic energy, and dissipated energy along with strain growth under uniaxial compression were obtained. Experimental results showed that when strain rate was 10-5/s and 10-4/s, the total energy, elastic energy and dissipated energy of concrete increased at first but then decreased with the rising of strain in the whole loading stage; while when strain rate was at 10-3/s, 10-2/s, the aforementioned values augmented with the rising of strain. Under the same lateral stress, the accumulated energy of concrete at failure and the energy storage of concrete increased along with the rising of strain rate; when concrete reached the limit of energy storage, the elastic energy density accounts for 30% at the minimum and 58% at the maximum. When strain rate is constant, the energy storage limit of concrete expanded with the climbing of lateral stress. Lateral stress restrained the development of cracks. When lateral stress was at (0.1, 0.3)fc, the elastic energy density of concrete increased linearly with the climbing of lateral stress.
关键词
混凝土 /
能量演化 /
应变速率 /
弹性能 /
耗散能
Key words
concrete /
energy evolution /
strain rate /
elastic energy /
dissipation energy
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