约束钢柱火灾下受力性能的参数分析

Parametric Studies on Restrained Steel Column in a Fire

摘要:

利用验证了的有限元模型对轴力和弯矩共同作用下的约束钢柱火灾下的受力性能进行了参数分析。 考虑的参数包括轴力荷载比，弯矩荷载比，轴向约束刚度比，转动约束刚度比， 长细比和端部弯矩比等。参数分析的结果包括各参数对钢柱的轴力－温度关系曲线和跨中截面－温度关系曲线的影响， 以及各参数对约束钢柱的 临界温度，无约束钢柱与约束钢柱临界温度之差，约束钢柱的临界温度与屈曲温度之差的影响等。 主要结论为：(1) 约束钢柱屈曲前，轴力基本线性增加，截面弯矩变化较小；(2) 约束钢柱屈曲后，截面弯矩突然增大，钢柱处于轴力和弯矩的共同作用下；(3) 轴向约束减小约束钢柱的临界温度，并且随之轴向约束刚度的增加，钢柱的临界温度逐渐减小，但 是存在一个临界轴向约束刚度比，当轴向约束刚度比大于该临界轴向约束刚度比时，轴向约束刚度比的大小对 钢柱的屈曲温度影响很小。

Abstract:

This paper investigates behaviours of restrained column in a fire using a calibrated finite element model. Studied parameters included axial load, bending moment load, axial restraint stiffness, rotational restraint stiffness, slenderness and end moment ratio. Presented results include the column axial force-temperature and bending moment-temperature evolution curves, critical temperature of restrained column, difference between critical temperatures of unrestrained column and restrained column, and difference between critical temperature and buckling temperature of restrained column. Results of parametric study show that: (1) before the column buckles, the axial force in column increase linearly and bending moment changes a little; (2) after the column buckles, the column is loaded under combined axial force and bending moment; (3) the axial restraint reduces the critical temperature of restrained column; and the reduction in critical temperature increases with increasing in axial restraint stiffness. However, when the axial restraint stiffness ratio is higher than a certain value, no further reduction in the column critical temperature occurs.