高温作用后混凝土动态压缩力学性能的试验研究

Experimental study on dynamic compressive mechanical properties of concrete after high temperature exposure

采用φ100 mm分离式霍普金森压杆(split Hopkinson pressure bar,简称SHPB)试验装置,分别对常温和经历200、400、600、800℃高温作用后的混凝土进行了冲击压缩试验,分析了高温和应变率对混凝土动态压缩力学性能的影响,并对其关系进行了拟合。结果表明:经历不同温度作用后的混凝土动态抗压强度、峰值应变以及比能量吸收都表现出较强的应变率效应。高温对混凝土动态力学性能影响显著,400℃是混凝土各项力学指标发生转折的温度:动态抗压强度、比能量吸收在400℃时回升至与常温接近,在400℃后又迅速下降;峰值应变在400℃以后增加明显,并随着应变率的提高而迅速增加。混凝土经400℃以上高温作用后,虽然强度损失严重,但在冲击荷载作用下,尤其是在较高应变率下,仍表现出良好的抗冲击韧性。

A 100 mm diameter split Hopkinson pressure bar（SHPB） apparatus was adopted to investigate the behavior of concrete at room temperature and after exposure to 200,400,600 and 800 ℃ under impact compressive loading.The effects of high temperature and strain rate on dynamic compressive mechanics properties were analyzed,and the relations between them were fitted.Results show that,the dynamic compressive strength,peak strain and specific energy absorption of concrete at different temperature show strong strain rate effects.The effects of high temperature on dynamic mechanical properties of concrete are significant.The critical temperature when the changes acquire dramatic character is 400 ℃：the dynamic compressive strength and specific energy absorption rise back at 400 ℃,and then drop rapidly after 400 ℃;peak strain of concrete increases evidently after 400 ℃,and increases rapidly with rise in average strain rate at the same time.Though the loss in strength of concrete after exposure to the temperature above 400 ℃ is severe,it still shows a nice anti-impact toughness under impact loading,especially at higher strain rate.