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为考察相邻构件的轴向约束作用对预应力轴心受力构件抗火性能的影响,建立了带轴向弹性约束的预应力轴心受拉钢构件的数值分析模型。边界条件是:对四面受火的轴心受拉钢构件下端支座约束3个方向自由度,上端支座约束构件横截面内自由度,而轴向采用弹性约束。考虑了荷载比、轴向约束刚度比2个关键参数,得到了系列轴力-时间关系曲线。数值分析结果表明:荷载比不变时,随着轴向约束刚度降低,构件的耐火时间提高;在约束刚度比不变条件下,荷载比对构件的临界时间影响较小。在轴向约束刚度比为0.02时,预应力轴心受拉杆件临界时间达到最大值;但在轴向约束为0时,预应力轴心受拉杆件耐火时间最短。
In order to investigate the influence of the axial constraint of adjacent members on the fire resistance of prestressed axial members, a numerical analysis model of prestressed axially tensioned steel members with axial elastic constraint was established. Boundary conditions are: the axis of the fire on all sides by the lower end of the steel member constraints constrained by the three directions of freedom, the upper end of the restraint member cross-section freedom, while the axial elastic constraint. Taking into account the load ratio, axial restraint stiffness ratio of two key parameters, a series of axial force - time curve was obtained. The results of numerical analysis show that when the load ratio is constant, the fire-resistant time of the component increases with the decrease of the axial restraint stiffness, while the load-time ratio has less influence on the critical time of the component under the condition of the same stiffness ratio. When the axial restraint stiffness ratio is 0.02, the critical moment of the prestressed axial center reaches the maximum value of the tie rod; however, when the axial constraint is 0, the prestressed axial center tie rod has the shortest refractory time.