含钢率对内配型钢方钢管混凝土柱耐火极限的影响

Influence of steel ratio on fire resistance of concrete-filled square steel tubular columns with internal profiled steel

采用ABAQUS有限元软件,建立了火灾作用下内配型钢方钢管混凝土轴压柱耐火性能的有限元模型,验证了有限元模型的可靠性。在保证钢材总含钢率不变的前提下,对钢管和内配型钢进行分配,对比分析了两种截面形式柱常温承载力和耐火极限。对钢管含钢率、型钢含钢率以及钢材材料强度进行了分析,并对不同截面总含钢率下钢管含钢率分配比例对耐火极限的影响进行了计算和分析。结果表明:保持总含钢率不变,将钢管中部分钢材以型钢的形式置于混凝土中,常温下承载力略有降低,但火灾下耐火极限提高甚为显著;当钢管含钢率占截面总含钢率的50%~60%时,常温下承载力和火灾下耐火极限均能得到充分的发挥。

A finite element( FE) model of concrete filled square steel tubular( CFST) columns with internal profiled steel was presented under fire using ABAQUS,and the FE model was verified by other researchers 'experimental results. The mechanical behavior of CFST columns with internal profiled steel were analyzed based on the total sectional steel dividing into steel tube and the internal profiled steel. The fire performance of CFST columns and CFST columns with internal profiled steel were studied respectively under the same section steel ratio condition. A series of parametric studies were performed considering steel tube ratio,internal profiled steel ratio and steel strength to study the influence rule of steel tube ratio on fire resistance of distribution. It can be found that fire endurance is improved obviously and the ultimate bearing capacity at ambient temperature is reduced slightly when part of steel in CFST columns is put in core concrete as internal profiled steel. The best steel tube ratio to obtain the optimal bearing capacity at ambient temperature and fire resistance is 50% ~ 60%.