不同高温作用后混凝土劣化损伤性能

Study on Deterioration and Damage Performance of Concreteat Different High Temperatures

混凝土作为普遍使用的建筑材料,为进一步探索其在受到高温冷却后劣化损伤性能,使用∅74 mm大口径分离式霍普金森压杆对不同温度冷却处理后的C30混凝土材料进行动态力学性能试验,得到其不同温度后、不同应变率下的应力-应变曲线,并针对其动态抗压强度、损伤变量及破碎形态进行了探讨。结果表明:在100~200℃范围内,混凝土的动态抗压性能下降有限,但当温度达到400℃及以上时,其力学性能下降明显,破碎形态严重。过高的温度会对混凝土材料造成损伤,高温冷却会使混凝土产生应变软化效应,高应变率下混凝土材料也体现出了应变率强化效应。过多的裂缝扩展也一定程度上抑制了损伤变量的增长。在相同温度处理后,应变率越高会使混凝土试样破碎越严重。且过高的温度会加剧混凝土的劣化损伤。

Concrete is a commonly used building material.In order to further explore its degradation and damage performance after high-temperature cooling,the dynamic mechanical properties of C30 concrete material after cooling at different temperatures were tested through the∅74 mm split Hopkinson pressure bar,and the stress-strain curves at different temperatures and different strain rates were obtained.The dynamic compressive strength,damage variables and crushing morphology of concrete are discussed.The results show that the dynamic compressive performance of concrete decreases limitedly in the range of 100~200℃,but its mechanical properties decreases significantly and its broken form is serious when the temperature reaches 400℃and above.Too high temperature can cause damage to the concrete material,the high temperature cooling causes the concrete to produce a strain softening effect,and the concrete material also shows the strain rate hardening effect under high strain rate.Excessive crack propagation inhibites the growth of damage variables to a certain extent.The higher strain rate makes the concrete sample be broken more seriously after the same temperature treatment.And the excessively high temperatures would aggravate the deterioration and damage of concrete.