轴力作用下的约束钢柱受火性能参数分析

Parametric Studies on Restrained Steel Column in Fire (Ⅰ)：Under Axial Load Only

摘要:

利用经过试验验证的有限元模型对轴力作用下约束钢柱火灾下的受力性能进行了参数分析.分析结果包括各参数对钢柱轴力—温度关系曲线、钢柱跨中弯矩—温度关系曲线、约束钢柱破坏温度、无约束钢柱与约束钢柱破坏温度之差、约束钢柱破坏温度与屈曲温度之差的影响等.参数分析表明：约束钢柱屈曲前，轴力基本线性增加，截面弯矩变化较小；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；轴向约束减小约束钢柱的破坏温度，但是存在一个临界轴向约束刚度比，当大于该临界比时，轴向约束刚度比的大小对钢柱的破坏温度影响很小.

Abstract:

This paper investigates behaviors of the restrained column under axial load in fire through using a calibrated finite element method model.Presented results include the column axial force-temperature evolution curve,column bending moment-temperature evolution curve,failure temperature of restrained column,difference between failure temperature of unrestrained and restrainedcolumn,and difference between failure and bucklingtemperature of restrained column.Results of parametric study show that:①before the column buckles,the axial force in column increases linearly and bending moment only varies a little;②after the column buckles,the bending moment in column increase suddenly,and the column is loaded under combined axial force and bending moment;③the axial restraint reduces failure temperature of restrained column;and the reduction in failure temperature increases with increasing of axial restraint stiffness.However,there is a critical restraint stiffness ratio,above which no further reduction in column failure temperature occurs.