CFDST组合截面结构柱的抗火设计分析

The analysis on fire-resistance design of concrete filled double skin steel tubes column section

基于钢管和混凝土的不同热工性能以及热传导的边界条件,采用有限单元法,建立CFDST柱截面二维计算模型,得出各节点在某一时刻的温度。根据高温下的钢材和混凝土本构关系,计算出不同温度下钢材和混凝土的应力,利用叠加原理求出CFDST组合结构柱的截面内力。结果表明CFDST组合结构柱外层钢管温度增长率高于混凝土和内层钢管的温度增长率;CFDST组合结构具有良好的耐火性能,主要影响因素包括构件长细比、内外层钢管强度、混凝土强度等级及空心率。

Comprehensively considering boundary conditions of heat conduction and different thermal properties of steel and normal concrete, the two - dimensional analysis - calculation model of concrete filled double skin steel tubes column section is established with the finite element method and the tem- perature of different node every moment was obtained. The stress of steel and concrete in certain tem- peratures can be concluded by using constitutive relation between steel and concrete on high tempera- ture and the internal forces of CFDST （concrete filled double skin steel tubes） combination structure column section can be concluded by using superposition principle. The results show that the fire re- sistance of components would be good by using this kind of steel. The concrete composite structure column section whose temperature of external steel tube is higher than concrete and inernal steel tube and the primary influencing factors of fire resistance are slenderness ratio, strength of internal and ex- ternal steel tubes and concrete and hollow ratio.