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目前对钢框架稳定的研究主要基于钢柱均匀升温的假定。然而,实际火灾下,由于热浮力效应,建筑物内部的温度分布可能不均匀。该文基于楼层屈曲和两区域火灾模型概念,研究柱纵向非均匀升温作用下无支撑钢框架的弹性稳定性。首先,为模拟非均匀升温下的钢柱,给出一个可检验轴向载荷、非均匀升温分布、热边界条件对无支撑框架钢柱侧向刚度影响的分析模型。基于欧拉-伯努利梁理论推导出柱模型的侧向刚度方程。然后,采用该模型评价非均匀升温作用下无支撑钢框架的稳定性。采用数值案例分析非均匀升温作用下不同钢框架的稳定性,有限元分析方法验证了所给方法分析结果的有效性。
At present, the research on the stability of steel frame is mainly based on the assumption that steel columns are uniformly heated. However, in actual fires, the temperature distribution inside the building may not be uniform due to the thermal buoyancy effect. Based on the concepts of floor buckling and two-zone fire model, the elastic stability of unsupported steel frame under longitudinal non-uniform heating is studied. First of all, to simulate the steel column under non-uniform temperature rise, an analytical model is provided to test the influence of axial load, non-uniform temperature distribution and thermal boundary conditions on the lateral stiffness of unsupported steel columns. The lateral stiffness equation of the column model is deduced based on the Euler-Bernoulli beam theory. Then, this model was used to evaluate the stability of unsupported steel frame under non-uniform heating. Numerical examples are used to analyze the stability of different steel frames under non-uniform heating. The finite element method is used to verify the effectiveness of the proposed method.