八边形钢管混凝土轴压短柱力学性能分析

Analysis of mechanical behavior of concrete-filled steel tubular stub columns of octagon section under axial compression

为深入认识八边形钢管混凝土轴压短柱的力学性能,建立了八边形钢管混凝土轴压短柱极限承载力计算公式,应用ABAQUS有限元软件对其进行三维实体有限元分析,基于有限元法参数分析,确定了八边形钢管混凝土轴压短柱极限状态时钢管平均轴向应力与屈服强度的比值.根据核心混凝土处于极限状态时的应力云图,将其简化为不受八边形钢管约束的非加强区核心混凝土和受八边形钢管均匀约束的加强区核心混凝土,并确定两者的面积比.根据力的叠加,提出一种新的八边形钢管混凝土轴压短柱承载力实用计算公式,并将该公式计算结果和16组国内外八边形钢管混凝土轴压短柱试验结果进行对比.结果表明:该实用计算公式计算结果与试验结果吻合良好.

In order to deeper understand the mechanical behavior of concrete-filled steel tubular （CFST） stub columns of octagon section under axial loads and to propose the formula of ultimate bearing capacity for CFST stub columns of octagon section, ABAQUS is used to establish the 3D finite element model and to analyze the behavior of CFST stub columns of octagonal section under axial compression. Based on ABAQUS parameter analysis, the ratio of average axial stress to yield stress of octagon steel tubular is de- termined for the CFST stub column of octagon section at ultimate state. According to the stress nepho- gram of concrete core section at ultimate state, which can be simplified to non-enhanced area of concrete core without confinement and enhanced area of concrete core with uniform confinement from octagon steel tubular. The ratio of the two areas is also determined. Based on superposition of load, a practical calcula- tion formula for ultimate bearing capacity of CFST stub columns of octagon section is proposed. The for- mula calculation results are compared with 16 groups of CFST stub columns of octagon section test results at home and abroad. The analytical results show that practical calculation formula presented in this paper agrees well with the experimental results.