| 摘要: |
| 对历经不同冻融循环次数的混凝土进行了不同应变速率的单轴循环加卸载试验，分析了试验所得应力-应变曲线外包络线的特征，定义了单轴循环加卸载的耗散能、弹性应变能和塑性应变能，研究了这3种能量与冻融循环次数和循环加卸载次数之间的关系。结果表明：混凝土应力-应变曲线外包络线整体上呈先升后降的趋势；随着冻融循环次数的增多，混凝土的峰值应力逐渐减小而峰值应变逐渐增大；应变速率不影响应力-应变外包络曲线的形状；冻融循环影响混凝土的率敏感性；随循环加卸载次数的增加，混凝土的耗散能、弹性应变能和塑性应变能整体上均呈先增后减的变化规律；冻融循环削弱了混凝土的脆性；外力做功90%的能量用于不可逆转的变化过程。 |
| 关键词: 冻融循环 循环加卸载 外包络线 能量演化 |
| DOI： |
| 分类号:TU528 |
| 基金项目:国家自然科学基金资助项目（51279092）； 三峡大学研究生科研创新基金项目（SDYC2016018） |
|
| Study of outer envelope curve and energy evolution for freeze-thaw deteriorated concrete under cyclic loading and unloading test |
|
LIU Qi1,2, PENG Gang1,2, XU Tonglin1,2, YANG Naixin1,2
|
|
1.Hubei Provincial Collaborative Innovation Center for GeoHazards and Eco-Environment in Three Gorges Area Yichang;2.College of Civil Engineering & Architecture, China Three Gorges University, Yichang
|
| Abstract: |
| The concrete deteriorated by freezing-thawing effect is tested under cyclic loading and unloading at different strain rates. The characteristics of the outer envelope line for strain-stress curves are analyzed. The dissipated energy, elastic strain energy and plastic strain energy are defined, and the relationship between each kind and the freeze-thaw cycles or the loading and unloading cycles is studied. It turns out that the outer envelope line rises at first and then drop down as a whole; the peak stress decreases but the peak strain increases gradually with the increase of freeze-thaw cycles; the strain rates have no effects on the shape of the outer envelope line; the strain-rate sensitivity for concrete is influenced by the freeze-thaw cycles; the dissipated energy, elastic strain energy and plastic strain energy increase at first and then drop down with the increase of loading and unloading cycles; the brittleness of concrete is weakened by freeze-thaw cycles; about 90% energy coming from the work of external force is used in irreversible process. |
| Key words: freeze thaw cycles loading and unloading cycles outer envelope curve energy evolution |
