循环荷载作用下冻融劣化混凝土能量耗散规律及破坏形态分析

为研究冻融劣化混凝土在循环荷载作用下的能量耗散规律及其破坏形态,对强度等级为C30的混凝土立方体(300mm×300mm×300mm)试件进行压缩试验。结果表明,当冻融循环次数不超过10次时,混凝土应力—应变曲线的外包络线呈两段式。当冻融循环次数超过10次时,包络曲线的应力与应变呈现出非线性增长,且这种非线性增长关系随冻融循环次数的增加而趋于明显;当冻融循环次数由10次逐渐增加至35次时,冻融劣化混凝土的破坏形态由剪压破坏逐渐向轴压破坏转变;冻融劣化混凝土试件在循环加卸载过程中耗散能、弹性应变能、塑性应变能的释放规律一致,都经历了前期能量释放缓慢,中期能量释放迅速,后期能量释放趋于平缓的变化阶段。研究成果可为严寒地区的混凝土构件设计及工程实践提供指导。

Energy Releasing Rules and Failure Pattern Analysis of Freeze-thaw Deterionrated Concrete under Cyclic Loading

In order to research the energy releasing regularity and failure pattern of freeze-thaw deterionrated concrete, compression testing was done for concrete under cycle loading. The concrete specimen strength grade is C30 and the size is 300 mm×300 mm×300 mm. The results show that when the freeze-thaw cycles are less than 10 times, stress-strain curve were divided into two stages; when the freeze-thaw cycles are more than 10 times, the envelope curve of stress and strain is in nonlinear growth, and nonlinear growth between stress and strain is more obvious with the increase of freeze-thaw cycles; when freeze-thaw cycles times increasing from 10 to 35, the freeze-thaw damage of concrete changed gradually form shear fractures to axial compression failure; the evolution rules of dissipation energy, elastic strain energy, plastic strain energy of freeze-thaw concrete are consistent with the number of loops and unloading, and its energy releasing experiences slowly stage, rapid stage and flat stage. The results can provide guidance for the design and engineering practice of concrete components in cold areas.