Experimental study on dynamic behaviours of concrete after exposure to high temperatures up to 700 °C

A Split Hopkinson pressure bar were used to experimentally study the dynamic behaviours of normal-strength concrete after exposure to elevated temperatures up to 700 °C. The dynamic strength and stress–strain relation curves of fire-damaged concrete were measured to unveil the effects of high temperature and strain rate on the dynamic behaviours of fire-damaged concrete. Test results showed that fire-damaged concrete still experienced remarkable strain rate effect and the dynamic stress versus strain relations of fire-damaged concrete were significantly different from those of concrete at room temperature. There was no obvious effect of temperature and strain rate on the shape of the ascending branches of normalized stress–strain relation curves of concrete after exposure to high temperatures. The tested results also showed that high temperature and strain rate had remarkable effect on the dynamic increase factor (DIF) for the fire-damaged concrete. The effect of high temperature on DIF of the fire-damaged concrete decreased as the temperature increased. The tested results can be a basis for assessing the impact resistance and anti-collapse resistance of fire-damaged concrete structures.