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大跨度建筑空间中的火灾属于局部火灾,局部受火的网架结构由于其整体性会产生杆件间的约束效应,实际工程中网架结构的杆件长细比往往大于钢框架柱。目前对于网架结构中的约束杆件屈曲后承载力未见研究报道。根据假定的高温下约束杆件的变形形态建立内外力平衡方程,提出考虑初弯曲的网架结构中轴向约束杆件屈曲后轴力的简化计算方法,得到受火全过程轴力—温度的关系曲线,并发现初弯曲会使得长细比较大的约束杆件的应力增长速率明显减小。通过ABAQUS软件对网架结构中轴向约束杆件受火力学反应全过程进行了数值模拟,本文提出的简化计算方法与数值模拟结果吻合较好,为进一步分析网架杆件屈曲后承载力对整体结构抗火性能的贡献提供了理论依据。
The fire in the long-span building space belongs to the partial fire. Due to its integrity, the grid structure of local fire will have the restraining effect between the bars. In practical engineering, the slenderness ratio of the grid structure is often larger than the steel frame column. At present, no research has been reported on the post-buckling bearing capacity of restrained bars in truss structures. Based on the assumed deformation of the constrained rod at high temperature, the internal and external force balance equations are established, and the simplified calculation method of the axial force after axial buckling in the truss structure considering initial bending is proposed. The axial force - temperature The relation curves and the results show that the initial bending will make the rate of stress growth of restrained rod with larger slenderness decrease obviously. The ABAQUS software was used to numerically simulate the whole process of axially restrained rod in the truss structure. The simplified calculation method proposed in this paper is in good agreement with the numerical simulation results. In order to further analyze the effect of bearing capacity The overall structural fire resistance contribution provides a theoretical basis.