高持续荷载下混凝土徐变和损伤耦合机理

为研究混凝土在高持续荷载作用下徐变和损伤的耦合机理.采用加卸载、碱骨料及高温烘烤获得了带不同初始损伤的混凝土,并开展了损伤混凝土在不同应力水平高持续荷载下的徐变试验,分析了混凝土徐变变形和损伤随持荷时间的变化规律,研究了单调加载和持续荷载下材料内部损伤演化和应变能累积的关系.结果 表明:混凝土在长期荷载作用下损伤随徐变应变增加而增大,在损伤稳定发展阶段徐变应变与损伤基本呈线性关系.混凝土在不同荷载形式下应变能和损伤的演化关系相同,可以通过混凝土单轴损伤-应变能关系来表征高持续荷载下徐变和损伤的耦合关系.研究成果可以为长期荷载下混凝土结构分析提供参考.

Study of the evolution of concrete damage under high sustained loads

The evolution of creep damage in concrete under high sustained loading is investigated in this paper. In this paper, concrete with different levels of initial damage was obtained by loading-unloading process, alkali aggregate reaction and high temperature baking. The creep tests of concrete with damage under different levels of high sustained loads were conducted to analyze the evolution of concrete creep deformation and damage with loading time. The relationship between strain energy accumulation and damage within the material under uniaxial and continuous loading was investigated. The results showed that the concrete damage under long-term loading increases with increasing creep strain, and the relationship between creep strain and damage is basically linear at the stage of stable damage development. The evolution of strain energy and damage of concrete under uniaxial load and different sizes of sustained loading have the same relationship, and the coupling of creep and damage under high sustained loading can be characterized by the relationship of uniaxial damage and strain energy for concrete. The results of this paper can provide references for design and safety evaluation of concrete structures under long-term loading.