历经荷载历史混凝土动态受压试验研究

Experimental research on dynamic compressive behaviors of concrete due to load histories

在应变率10-5～10-2 s-1,混凝土立方体试件历经0、30%、50%和75%极限抗压强度的荷载历史,在静动态三轴试验系统上进行相同应变率动态抗压试验,研究了不同荷载历史对混凝土在不同应变率时的动态抗压强度、初始弹性模量、临界应变以及应力应变全曲线等动态特性以及应变率的影响.试验结果表明不同应变率下历经荷载历史后,混凝土应力应变全曲线变化明显;随着应变率的增加,动态单轴抗压强度显著增加,但当荷载历史超过某一槛值后,混凝土极限抗压强度明显降低;混凝土初始弹性模量随着应变率的增加明显地提高,但随着荷载历史的变化并没有明显的变化;混凝土的临界应变随着应变率和荷载历史的增加而减小,且荷载历史对临界应变的影响远远大于应变率对临界应变的影响.

The dynamic compressive test of concrete specimens,due to load histories of 0,30%,50%and 75% ultimate strengths,is carried out on the static-dynamic triaxial test system with the strain rates ranging from 10-5 s-1 to 10-2 s-1.The strain-stress full curves,the compressive strength,the initial elastic modulus and the critical strain of concrete at different strain rates and load histories are analyzed and the effects of strain rates and load histories on these behaviors are studied.Experimental results show that the strain-stress full curve of concrete is affected obviously by strain rates and load histories.The compressive strength of concrete increases with the strain rate and decreases when the load history exceeds the load history threshold.The initial elastic modulus of concrete increases with the strain rate,but it is independent on the load history.The critical strain of concrete increases with the strain rate and the load history,and the influence of the load history on the critical strain is greater than that of the strain rate.