三面受火的方中空夹层钢管混凝土柱耐火极限分析

In order to investigate fire performance of concrete-filled double skin tubular columns exposed to three-sided fire, a finite element model was established using ABAQUS software. The calculated and experimental results were compared, and good agreements were achieved. The established models were used to analyze the thermal field and stress mechanism of this kind of members. And effects of common parameters on the fire resistance of the components under three-sided fire were investigated. A simplified formula for calculating the fire resistance of concrete-filled double skin tubular columns exposed to three-sided fire was proposed. The results show that, in the ranges of commonly used parameters of load ratio (0.4-0.8), slenderness ratio (20-50), and section size (400-1 000 mm), the load ratio, slenderness ratio, section size and load eccentricity are the main influencing parameters of the fire endurance of the component. The smaller the load ratio, the slenderness ratio and the larger the cross-sectional dimension, the greater the fire resistance of the components. When 0≤e/r₀≤0.4, the load eccentricity has a great influence on the fire endurance of the component, and the fire resistance limit is 50% higher than that of the axial pressure.