高强混凝土RC梁冲击试验研究及其数值模拟

发布时间：2018-07-17 15:25

【摘要】：近几年来,国内外恐怖袭击及恶性爆炸事件给世界范围内的人民生命财产安全带来灾难性的威胁。除此之外,自然灾害如地震、海啸、泥石流及其产生的次生灾害在毁坏建筑物的同时对人们的生命财产安全同样造成巨大危害。由于全世界范围内建筑物多采用钢筋混凝土结构,因此钢筋混凝土结构在冲击荷载下力学行为及破坏特征研究很有必要。作为结构的重要受力构件,钢筋混凝土梁在设计时应适当考虑冲击、爆炸等荷载的影响。钢筋混凝土梁在冲击荷载下破坏形态及混凝土裂缝发展模式在以往的研究中已经得到基本体现。但随着高强混凝土在结构中应用的发展,对高强混凝土RC梁的冲击性能研究需要进一步深入。本文在此基础上重点对高强混凝土RC梁的抗冲击行为进行研究,为此设计了一组高强混凝土RC梁。试验研究了不同因素下梁在冲击荷载下的抗冲击能力、冲击力、支座反力、跨中位移、裂缝发展模式及破坏形态。本文利用落锤试验模拟冲击荷载对梁进行试验。试验变量包括配箍率、冲击能量、混凝土强度等。同时利用高速摄影机对试验中破坏过程进行了全程影像记录。落锤试验中,通过仪器获得高强混凝土RC梁在冲击荷载下跨中位移时程、冲击力时程、支座力时程、钢筋混凝土梁纵筋及箍筋应变时程曲线,得到梁沿长度方向的应变分布。试验结果表明:配箍率与混凝土等级的差异可改变钢筋混凝土梁裂缝产生机制。配箍率的提高可有效减小梁跨中位移峰值。在冲击试验基础上,本文利用显式动力有限元分析软件LS-DYNA,对高强混凝土RC梁冲击试验进行了数值仿真分析。模拟结果表明有限元模型与试验结果拟合情况良好,其中试验梁在冲击荷载下的跨中位移、冲击力、支座力时程曲线能做到很好的预测。但混凝土材料模型的部分缺陷对高强混凝土RC梁的破坏特征并不能做到精确预测,需要进一步完善与研究。同时利用数值模拟分析模型对混凝土强度、落锤重量、冲击速度、配箍率的具体影响进行参数分析。
[Abstract]:In recent years, terrorist attacks and vicious bombings at home and abroad have brought a disastrous threat to the lives and property of people all over the world. In addition, natural disasters such as earthquakes, tsunamis, mudslides and their secondary disasters not only destroy buildings, but also cause great harm to the safety of people's lives and property. As reinforced concrete structures are mostly used in buildings all over the world, it is necessary to study the mechanical behavior and failure characteristics of reinforced concrete structures under impact loads. As an important structural member, the impact of impact and explosion should be taken into account in the design of reinforced concrete beam. The failure mode of reinforced concrete beams under impact load and the development mode of concrete cracks have been basically reflected in the previous studies. However, with the development of the application of high strength concrete in the structure, the research on the impact performance of high strength concrete RC beams needs to be further studied. In this paper, the impact behavior of high strength concrete RC beams is studied, and a group of high strength concrete RC beams are designed. The impact resistance, impact force, bearing reaction force, mid-span displacement, crack development mode and failure mode of beams under different factors were studied. In this paper, the impact load is simulated by drop weight test to test the beam. Test variables include hoop ratio, impact energy, concrete strength and so on. At the same time, a high-speed camera is used to record the whole process of the damage in the experiment. In the drop weight test, the time history of displacement, impact force, bearing force, longitudinal reinforcement and stirrups strain history of RC beams with high strength concrete under impact load are obtained, and the strain distribution of RC beams along the length direction is obtained. The experimental results show that the crack generation mechanism of reinforced concrete beams can be changed by the difference of hoop ratio and concrete grade. The increase of hoop ratio can effectively reduce the peak displacement of beam span. On the basis of impact test, the impact test of RC beam with high strength concrete is simulated by using explicit dynamic finite element analysis software LS-DYNA. The simulation results show that the finite element model fits well with the test results, and the time-history curves of the mid-span displacement, impact force and support force of the test beam under impact load can be well predicted. However, the failure characteristics of high strength concrete RC beams caused by some defects of concrete material model can not be accurately predicted, and need to be further improved and studied. At the same time, the influence of concrete strength, weight of drop weight, impact speed and hoop ratio is analyzed by numerical simulation model.
【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】：TU375.1

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