钢框架柱抗火承载力的非线性有限元分析

为深入了解火灾下钢框架柱的受力性能和破坏模式以及各种因素对其抗火承载力的影响,采用有限元方法对H型钢框架柱在火灾中的反应进行了理论分析.结果表明:火灾中相连梁膨胀产生的推力对框架柱的耐火极限具有明显的降低作用,且随着框架柱荷载水平的增加这种影响加剧;由于内力重分布的影响,框架柱轴力在火灾初期持续增长,火灾后期反而降低甚至低于常温状态,且在火灾中随着温度的升高框架柱的端弯矩持续减小;火灾中H型钢框架柱的翼缘端部、中部发生明显的局部失稳现象,局部失稳的位置将影响抗火设计中柱的计算长度的取值.

Nonlinear finite element analysis on the fire-resistance capacity of steel frame columns

In order to thoroughly understand the stress performance and the failure pattern of the H-section steel column in fire and the influence of various factors on its load-bearing capacity in fire.The theoretical analysis on the response of H-section steel columns in fire was performed using the finite element method.The results show that the fire-resisting limitation of frame column is decreased significantly due to the pushing forces caused by the expansion of the connected beams,and this influence is strengthened with the increasing load of the frame column.Because of the redistribution of internal force,the axial force of the frame column increases continuously in the early stage of fire,but decreases in the final stage of fire,at the same time the end moment of the column decreases continuously with the increase of the temperature.The clear crippling phenomenon may occur generally at the end and the middle flanges of the H-section steel column in fire,and the position of crippling of the flange may affect the value of the calculation length of the column in the fire-resistance design.