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Compressive Response of Composites Under Combined Fire and Compression Loading

机译:火与压缩共同作用下复合材料的压缩响应

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摘要

The thermal buckling of an axially restrained composite column that is exposed to a heat flux due to fire is studied by both analytical and experimental means. The column is exposed to fire from one-side and the resulting heat damage, the charred layer formation and non-uniform transient temperature distribution are calculated by the thermal model developed by Gibson et al. (Revue de lTnstitute Francais du Petrole 50:69-74, 1995). For the thermal buckling analysis, the mechanical properties of the fire-damaged (charred) region are considered negligible; the degradation of the elastic properties with temperature (especially near the glass transition temperature of the matrix) in the undamaged layer, is accounted for by using experimental data for the elastic moduli. Due to the non-uniform stiffness and the effect of the ensuing thermal moment, the structure behaves like an imperfect column, and responds by bending rather than buckling in the classical Euler (bifurcation) sense. Another important effect of the non-uniform temperature is that the neutral axis moves away from the centroid of the cross section, resulting in another moment due to eccentric loading, which would tend to bend the structure away from the fire. In order to verify the mechanical response, the compressive buckling behavior of the same material subjected to simultaneous high intensity surface heating and axial compressive loading were investigated experimentally. Fire exposure was simulated by subjecting the surface of rectangular specimens to radiant heating in a cone calorimeter. Heat flux levels of 25 kW/m2, 50 kW/m2 and 75 kW/m2 were studied. All specimens exhibited buckling and subsequent catastrophic failure, even at compressive stresses as low as 3.5 MPa under a surface heat flux of 25 kW/m2. Details of the experimental procedure, including modifications made to a cone calorimeter to allow simultaneous mechanical loading are presented.
机译:通过分析和实验方法研究了轴向约束复合柱由于火灾而暴露在热流中的热屈曲。色谱柱从一侧暴露于火中,由此产生的热损伤,炭化层的形成和不均匀的瞬态温度分布是根据Gibson等人开发的热模型计算的。 (Revue de lTnstitute Francais du Petrole 50:69-74,1995)。对于热屈曲分析,火灾(烧焦)区域的机械性能可以忽略不计;通过使用弹性模量的实验数据来解释在未损坏层中弹性性能随温度的下降(​​尤其是在基质的玻璃化转变温度附近)。由于不均匀的刚度和随之而来的热力矩的影响,该结构的行为就像不完美的圆柱,并且在经典的欧拉(分叉)意义上通过弯曲而不是屈曲来响应。温度不均匀的另一个重要影响是,中性轴远离横截面的质心,由于偏心载荷而导致另一个力矩,这将使结构远离火势。为了验证机械响应,实验研究了相同材料同时承受高强度表面加热和轴向压缩载荷的压缩屈曲行为。通过在锥形量热仪中对矩形样品的表面进行辐射加热来模拟火灾暴露。研究了25 kW / m2、50 kW / m2和75 kW / m2的热通量水平。即使在表面热通量为25 kW / m2的情况下,即使在低至3.5 MPa的压缩应力下,所有试样都表现出屈曲和随后的灾难性破坏。介绍了实验程序的详细信息,包括对锥形量热仪进行修改以允许同时进行机械加载。

著录项

  • 来源
    《Fire Technology》 |2011年第4期|p.985-1016|共32页
  • 作者单位

    Georgia Institute of Technology, Atlata, GA, USA;

    Georgia Institute of Technology, Atlata, GA, USA;

    Georgia Institute of Technology, Atlata, GA, USA;

    Missouri University of Science and Technology, St. Louis, MO, USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    fire; buckling; thermal; composites; column;

    机译:火;屈曲热复合材料柱;
  • 入库时间 2022-08-18 00:13:01

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