钢纤维混凝土高温后SHPB试验研究

为了研究钢纤维混凝土(SFRC)常温以及经历400和800℃高温后的动态压缩性能,采用改进的分离式Hopkinson压杆装置,结合应变直测技术对其进行了单轴冲击压缩试验.结果表明:经历400和800℃高温后,未掺钢纤维混凝土的峰值应力分别只有常温时的79.2%和38.9%,弹性模量分别降为常温时的82.8%和56.2%,同时,试件的能量吸收能力大幅度下降;钢纤维混凝土400,800℃对应的峰值应力分别降为常温时的76.8%和39.0%,弹性模量稍有降低,分别为常温的91.8%和82.7%,较基准混凝土有了较大的提高.钢纤维的加入可以增加混凝土的极限应力对应应变,曲线的下降段较为平缓,同时增强了混凝土的能量吸收能力,在20,400和800℃时,分别提高了38.5%,27.5%和25%.

Split Hopkinson Bar Measurements of Steel Fiber Reinforced Concrete Exposed to High Temperature

A modified split Hopkinson pressure bar(SHPB) method was combined with strain gauge measurements to investigate the behavior of steel fiber reinforced concrete(SFRC) under uni-axial high-strain-rate compressive loading. The concrete was exposed to a temperature of 400℃ or 800 ℃. The experimental results show that the compressive strength and elastic modulus of non-steel-reinforced concrete drop to 79.2% and 82.80/60 of the room temperature values when exposed to 400 ℃. At 800 ℃, the compressive strength and elastic modulus drop to 38.9% and 56.2 % of the room temperature values. At the same time, the energy absorbing ability of the concrete has dropped to a great extent after exposure to the high temperatures. In comparison, the compressive strength of steel-reinforced concrete drops to 76.8% or 39.0% of the room temperature value after heating to 400 ℃ or 800 ℃. Compared to control concrete the elastic modulus of the steel-reinforced concrete decreased slightly, to 91.8% or 82.7% after heating to 400 ℃ or 800 ℃. The energy absorption ability also deteriorates after exposure to high temperature. Steel fiber reinforcement increases the ultimate strain and energy absorbing ability of concrete. The energy absorbing ability is increased by 38.5%, 27.5% or 25%, com-pared to non-reinforced concrete, after exposure to 20, 400 or 800℃ temperature.