轻质高强混凝土大直径霍普金森杆冲击试验研究

轻质高强混凝土材料已经广泛运用于各种建筑结构中，然而其冲击作用下的动力性能尚不明确。为了探讨其动力性能，设计制作了一系列圆柱体混凝土试件。首先通过静力加载试验获得了其静力强度，然后，采用155mm大直径分离式霍普金森杆(SHPB)设备，对直径为150mm、长径比为0.5的混凝土试件开展了冲击试验研究。采用紫铜片作为波形整形器，该试验中各气压下冲击速度稳定，SHPB试验结果可靠。混凝土试件的破坏模式以脆性碎裂为主，随着冲击速度的增加，破坏后的碎块由条片状逐渐过渡至粉末状。应变率在40～140s-1时，试件的动态强度随着应变率的增大而增大。当冲击速度增加时，能量吸收密度也随之增加，即材料吸收能量的能力显著提高。根据试验结果，拟合了动态应力-应变曲线，以期供相关研究参考。

Impact tests of high-strength,lightweight concrete with#br#large spilt Hopkinson pressure bar

Lightweight, high-strength concrete materials have been widely used in building structures, while their dynamic behaviors under impact action haven’t been fully understood. To investigate the dynamic behavior, a group of high-strength, lightweight concrete cylinders were fabricated. The compressive strength was acquired through uniaxial static loading. Meanwhile, the 150mm-diameter specimens with the length to diameter ratio of 0.5 were tested by using a newly developed large split Hopkinson pressure bar (SHPB) with a diameter of 155 mm. Copper disc was applied as the pulse shaper and the resulting impact velocity was validated to be stable in each test scenario. The damages of the concrete specimens mainly appear to be brittle, and the fragments with different sizes were generated after each impact. The higher the impact velocity, the smaller the sizes of the fragments tend to be. The dynamic strength increases with the strain rate which ranges from 40 to 140 s-1-the energy absorption density increases with the impact velocity, demonstrating the increase of the energy dissipation capacity of the specimen. The dynamic stress-strain curves were regressed based on the experimental results, which can be referred to by the relevant dynamic analysis.