Abstract: Concrete strength under long-term sustained loading was investigated in this paper. By analyzing deformation behavior and damage evolution mechanism of concrete under sustained loading，and by comparing concrete creep and fatigue behavior similarity，the damage evolution ratio was assumed in proportion to strain increasing ratio. The envelope of concrete stress-strain relationship was analyzed with consideration of microcracks evolution in concrete material. The relationship between stress level and critical damage strain was then established. Concrete real strength under sustained loading was achieved. Comparing with existed experiments shows a good correlation.

Key words: concrete, strength, damage, sustained loading, creep

摘要： 通过比较混凝土在持续荷载的损伤与疲劳损伤的联系，假定在持续荷载下混凝土的损伤速率和应变增长速 率成正比;分析了混凝土在持续荷载下的变形行为和损伤机理，及混凝土在不同荷载历史情况下的破坏边界面;建 立了荷载水平和临界损伤应变之间的关系;研究了不同荷载水平下混凝土的真实强度以及不同强度混凝土在持续 荷载下的性能。与试验结果对比，建立的模型可以较好地反映混凝土在持续荷载下的性能。

关键词: 混凝土, 强度, 损伤, 持续荷载, 徐变