高温后混凝土SHPB试验研究

SHPB test for post-high-temperature concrete

采用Φ100 mm分离式霍普金森压杆(split Hopkinson pressure bar,简称SHPB)试验装置,对常温和经历200℃、400℃、600℃、800℃高温作用后的混凝土进行冲击压缩试验,得到动态压缩应力-应变曲线,分析弹速、温度对平均应变率的影响以及温度、平均应变率对动态抗压强度的影响。结果表明:弹速与平均应变率之间、平均应变率与动态抗压强度之间都近似呈线性关系。温度对混凝土动态性能影响显著,在相同弹速下与常温情况相比,200℃时平均应变率有所提高、动态抗压强度有所降低,400℃时与常温接近,400℃以后平均应变率随着温度增加而提高,而动态抗压强度随着温度的增加而急剧下降,至800℃不足常温试件的30%。高温将降低混凝土的应变率敏感性,其中以400℃降低最为明显。

A 100 mm-diameter split Hopkinson pressure bar（ SHPB ） apparatus was adopted to investigate the behavior of concrete exposed to 200℃, 400℃, 600℃ and 800℃, the dynamic compressive stress-strain curves were obtained, the effects of striking velocity and temperature on average strain rate and the effects of temperature, average strain rate on dynamic compressive strength were analyzed. The results showed that the relationship between striking velocity and average strain rate and that between average strain rate and dynamic compressive strength are approximately linear; the effect of high temperature on dynamic properties of concrete is significant; compared with the test at room temperature under the same striking velocity, average strain rate of concrete exposed to 200℃ increases while its dynamic compressive strength decreases, after a recover at 400℃, average strain rate increases with increase in temperature, while dynamic compressive strength decreases severely and at 800℃ it becomes less than 30% of that at room temperature ; high temperature reduces the strain rate sensitivity of concrete, especially, 400℃ does.