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混凝土材料是多相复合材料,高温动荷载作用下其力学行为非常复杂。为此,对混凝土在爆炸、火灾等高温环境中力学特性的研究,有利于减小混凝土结构在爆炸及火灾事故中的损失。文中首先利用分离式霍普金森压杆试验装置(SHPB)设计出一套混凝土高温试验方案,然后基于15组试验工况对混凝土在温度为16℃至650℃范围内,加载撞击速度分别为5m/s、7m/s和12m/s时进行了SHPB试验,获得了与之对应的应力应变曲线。试验结果表明,混凝土应变率增强效应与高温弱化效应相互耦合,致使混凝土受温度的影响显著大于其应变率。最后,由试验结果以经典损伤理论模型为基础,根据混凝土高温动态力学特性,构建了一个统一的方程来描述混凝土高温动态应力应变关系的全过程,并且该本构方程计算结果与试验数据吻合良好。
Concrete is a multi-phase composite material, the dynamic behavior under high-temperature dynamic load is very complicated. Therefore, the study of mechanical properties of concrete in high temperature environment such as explosion and fire will help to reduce the loss of concrete structure in explosion and fire accidents. In this paper, a set of test program of high temperature concrete was designed by using the split Hopkinson pressure bar test equipment (SHPB). Based on the 15 test conditions, the concrete was heated in the temperature range of 16 ℃ to 650 ℃ and the impact velocities were 5m / s, 7m / s and 12m / s SHPB test was carried out to obtain the corresponding stress-strain curve. The test results show that the concrete strain rate enhancement effect and the high temperature weakening effect are mutually coupled, resulting in the influence of concrete temperature being significantly greater than its strain rate. Finally, based on the classical damage theory model, a unified equation is constructed to describe the whole process of the dynamic stress-strain curve of concrete at high temperature according to the experimental results based on the theoretical model of high-temperature dynamic damage. The calculated results are in good agreement with the experimental data .