高温后混凝土材料的冲击力学性能试验研究

发布时间：2018-01-05 03:20

本文关键词：高温后混凝土材料的冲击力学性能试验研究　出处：《湖南大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来,恐怖袭击事件及建筑火灾事故频发,在高温和冲击荷载作用下建筑结构一旦丧失承载能力发生整体坍塌将造成巨大的生命财产损失。混凝土材料高应变率下的动态力学性能和高温静态力学性能研究已经比较成熟,但混凝土在冲击荷载和火灾联合作用下的力学性能研究比较少见,且目前有限的研究也大多采用小杆径(小于100mm)的SHPB装置进行。本文运用湖南大学φ100mm大杆径分离式霍普金森压杆(Split Hopkinson Pressure Bar,简称SHPB)装置进行了高温后混凝土的冲击力学性能试验,同时还进行了高温后混凝土的微观结构试验研究,主要包括以下几个方面的研究工作:(1)鉴于材料冲击荷载作用下应变率效应分析的需要,首先进行高温后混凝土的静态抗压强度试验,并对国内外有关高温后混凝土静态抗压试验研究文献进行统计,探究高温后混凝土残余抗压强度变化规律的复杂性。(2)以温度和冲击速度为试验参数进行高温后混凝土的SHPB冲击压缩力学性能试验,分析温度和应变率对高温后混凝土动态冲击应力-应变曲线特征的影响规律。(3)与其它学者小杆径SHPB冲击试验结果进行对比,探究高温后混凝土的动态强度增大系数(DIF)的变化规律,进行高温后混凝土SHPB冲击作用下的应变率效应和尺寸效应分析。(4)进行高温后混凝土及水泥浆体的热重分析(TG)、电镜扫描(SEM)和压汞(MIP)试验,得到高温后混凝土的组成成分和微观结构变化规律,揭示高温后混凝土动、静态力学性能的高温损伤机理。
[Abstract]:In recent years, terrorist attacks and building fire accidents occur frequently. Under the action of high temperature and impact load, the whole collapse of building structure will cause great loss of life and property. Study on dynamic and static mechanical properties of concrete materials at high strain rate. It's mature. However, the mechanical properties of concrete under the combined action of impact load and fire are rare. At present, most of the limited researches are carried out with SHPB device with small rod diameter (less than 100mm). In this paper, the split Hopkinson pressure bar with 蠁 100mm large diameter is used in Hunan University. Split Hopkinson Pressure Bar. The impact mechanical properties of concrete after high temperature were tested and the microstructure of concrete after high temperature was studied. In view of the need of strain rate effect analysis under the impact load of materials, the static compressive strength test of concrete after high temperature is carried out. And the domestic and foreign literature on static compressive test of concrete after high temperature is statistically analyzed. Explore the complexity of the variation law of residual compressive strength of concrete after high temperature. (2) take temperature and impact velocity as test parameters to test the SHPB impact compression mechanical properties of concrete after high temperature. This paper analyzes the influence of temperature and strain rate on the characteristics of dynamic shock stress-strain curve of concrete after high temperature. To explore the dynamic strength increase coefficient of concrete after high temperature and the change law of DIFs. The strain rate effect and size effect of concrete under the impact of SHPB after high temperature are analyzed. (4) the thermogravimetric analysis of concrete and cement paste after high temperature is carried out. The composition and microstructure of concrete after high temperature were obtained by scanning electron microscopy (SEM) and mercury injection MIP tests, and the damage mechanism of dynamic and static mechanical properties of concrete at high temperature was revealed.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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