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对火灾升温条件下压弯约束钢柱的轴力和截面弯矩发展规律进行了研究,给出了确定其屈曲温度和破坏温度的简化方法。约束钢柱屈曲前,随着温度升高钢柱轴力线性增加,截面弯矩基本保持不变;约束钢柱屈曲后,钢柱轴力减小,截面弯矩突然增大,钢柱处于轴力和弯矩共同作用下。确定屈曲温度时,采用无约束压弯钢柱屈曲温度的计算公式,钢柱轴力考虑轴向约束的影响;确定破坏温度时,破坏准则采用截面屈服条件表示的轴力-弯矩相关关系,轴力取初始轴力。利用有限元方法对本文公式进行了验证,对通常情况下的约束钢柱(荷载比小于0.7,约束刚度比小于0.1),本文方法与有限元方法计算结果吻合较好。
The law of axial force and moment of moment under compression bending confined steel column under fire heating condition was studied, and a simplified method to determine the buckling temperature and failure temperature was given. Before the buckling of the confined steel column, the axial force of the steel column increases linearly with the increase of temperature, and the moment of section remains almost unchanged. After the buckling of the confined steel column, the axial force of the steel column decreases and the moment of section suddenly increases. Under the joint action of bending moment When the buckling temperature is determined, the buckling temperature of unconfined bent steel columns is taken into account. The axial force of the steel column is taken into account of the axial restraint. When the failure temperature is determined, the failure criterion is expressed by the cross-section yield condition. Axial force take the initial axial force. The finite element method is used to verify the formula in this paper. For the constrained steel columns (the load ratio is less than 0.7 and the restrained stiffness ratio is less than 0.1), the calculated results are in good agreement with the finite element method.