历经单调荷载历史后混凝土动态损伤特性的研究

Research on the Dynamic Damage Characteristics of Concrete after Experiencing Monotonic Loading History

研究了历经不同单调荷载历史后混凝土试件在不同应变速率（10^-5／s、10^-4／s、10^-3／s）下的动态单轴受压试验，对比分析了混凝土应力～应变全曲线，并采用改进后的Weibull统计模型分析了单轴受压损伤特性。试验结果表明：在相同荷载历史下，随着应变速率的提高，混凝土峰值应力及弹性模量明显增加，峰值应变变化不明显；在相同的应变速率下混凝土峰值应力、峰值应变和弹性模量随荷载历史幅值的增加而降低，历经85％的单调荷载历史幅值后，混凝土残余强度降低显著；当单调荷载历史低于某一槛值时，荷载历史对混凝土强度影响较小，但是加载历史高于某一槛值时，混凝土损伤变量随应变速率的提高而增加，混凝土极限抗压强度明显降低。

The dynamic uniaxial compression tests of concrete were researched under different strain rates （10-5/s.10-4/s. 10-3/s） after experiencing different monotonic loading history, the stress-strain curve of concrete were analyzed, and the improved Weibull statistical model was used to analyze the uniaxial compression damage characteristics. The results show that the peak stress and elas- tic modulus of concrete improved with the increase in strain rates under the same load history condition, but the variation of peak strain was not obvious; the peak stress, peak strain and elastic modulus of the concrete decreased with the increase in loading history amplitude at the same strain rate, concrete residual strength decreased significantly after experiencing 85 % of the monotonic loading amplitude; the loading history has little influence on the strength of concrete when loading history amplitude is below a certain threshold value, but the damage variable increased and the ultimate compressive strength decreased obviously along with the increase in strain rates when the loading history amplitude is higher than a certain threshold value.