基于FDS升温曲线的轴压柱等效火灾荷载计算

发布时间：2018-05-11 16:17

  本文选题：混凝土轴压柱 + 升温曲线　； 参考：《华中科技大学》2013年硕士论文

【摘要】：建筑火灾发生频繁，从而带来严重损失。由于混凝土结构是广泛使用的结构形式，深入了解混凝土结构构件抗火性能对于防灾减灾具有重要意义。目前结构抗火性能研究中大多数假定周围温度环境为标准升温曲线形式，计算误差偏大，也不够合理。本文采用FDS消防软件来模拟发生火灾时构件表面的实际升温曲线，以此作为结构构件温度场有限元分析的边界条件来计算构件内部的温度场。在此基础上，将火灾的高温作用等效为荷载，研究考虑火灾高温作用的统一结构设计方法。 本文首先运用FDS，模拟单室火灾发展过程，，得到环境升温曲线；以实际升温曲线为第三类边界条件并利用有限元分析软件ANSYS计算构件截面温度场的分布，为等效火灾荷载的简化计算提供基础；通过理论和数值分析，改进了等效火灾荷载的简化计算方法，进一步修正已有的计算公式，四面受火柱的算例分析表明运用简化公式计算的结果精度符合工程要求。 本论文得到的主要结论如下：火灾发展过程中，室内各点的温度随时间不断升高，测点位置、开口状态、火源位置以及大小均会对实际的温升曲线有影响。对结构抗火性能设计中一律采用标准升温曲线作为环境温度不够准确。运用ANSYS进行结构热分析表明：混凝土是热惰性材料，随着时间的推移，截面内同一等温线不断向内部推进。对截面削弱过多的500℃界限，本文采用两台阶简化模型，以减少截面削弱过多结果过于保守的情形。计算结果表明，对于四面受火柱此种简化方法可以有效提高约10%的精度。
[Abstract]:Building fires occur frequently, resulting in serious losses. As concrete structures are widely used, it is very important to understand the fire resistance of concrete structural members for disaster prevention and mitigation. At present, most of the researches on the fire resistance of structures assume that the surrounding temperature environment is a standard heating curve, and the calculation error is too large and unreasonable. In this paper, FDS fire protection software is used to simulate the actual heating curve of the component surface in case of fire, which is used as the boundary condition for the finite element analysis of the temperature field of the structural member to calculate the temperature field inside the member. On this basis, the high temperature action of the fire is equivalent to the load, and the unified structure design method considering the fire high temperature is studied. In this paper, we first use FDS to simulate the development process of single chamber fire, and get the environmental heating curve, taking the actual heating curve as the third kind of boundary condition and using the finite element analysis software ANSYS to calculate the temperature field distribution of the section of the component. It provides the foundation for simplified calculation of equivalent fire load, improves the simplified calculation method of equivalent fire load through theoretical and numerical analysis, and further modifies the existing calculation formula. The analysis of fire column on four sides shows that the accuracy of the simplified formula is in line with the engineering requirements. The main conclusions obtained in this paper are as follows: during the development of fire, the temperature of each point in the room increases with time, and the location of the measuring point, the opening state, the location of the fire source and the size of the fire will affect the actual temperature rise curve. It is not accurate to use the standard temperature curve as the ambient temperature in the design of structure fire resistance. The structural thermal analysis with ANSYS shows that concrete is a thermal inert material, and the same isotherm in the section pushes forward to the inside with time. In this paper, a simplified two-step model is used to reduce the over-conservative results of section weakening by using a two-step simplified model for the 500 鈩

本文编号：1874671