轴力作用下基于子结构模型的约束PEC柱耐火极限研究

利用有限元软件ABAQUS,建立了包含部分梁、柱的约束PEC柱子结构温度场和力学分析模型,应用约束PEC柱的抗火试验数据验证了模型的合理性。采用上述模型分析了轴力比、轴向约束刚度、约束梁跨度、柱长度以及梁上荷载大小对轴力作用下约束PEC柱耐火极限的影响规律,并建立了该类构件的耐火极限简化计算公式。结果表明,轴力比和柱长度对轴力作用下约束PEC柱的耐火极限有较大影响,而轴向约束刚度、约束梁跨度及梁上荷载的影响很小;轴力比是影响柱耐火极限的重要参数,耐火极限随荷载比的增大迅速降低。给出的耐火极限计算公式可供约束PEC柱耐火设计参考。

Research on fire resistance of restrained PEC columns under axial load based on sub-structure models

By using the software ABAQUS, a finite element model was established to calculate the temperature field and mechanical behavior of the sub-structures including partial beams and retrained PEC columns, and the model was verified by the fire test data of retrained PEC columns. The model was then used to analyze the influence of the parameters such as axial load ratio, axial restraint stiffness, retrained beam span, column length and beam load on the fire resistance of the sub-structure subjected to axial load under the fire condition. A simplified method to determine the fire resistance of PEC columns was established. It can be seen from the research results that the axial load ratio and column length have large influence on the fire resistance of axially restrained PEC columns, while the axial restraint stiffness, retrained beam span and beam load have little influence on the columns. Increase of the axial load ratio leads to a rapid decrease of fire resistance. Simplified calculation method promoted in this paper can be used as a reference to the fire design of axially restrained PEC columns.