带约束拉杆方形钢管混凝土短柱偏压工作机理

Eccentric compressive mechanism of square CFT columns with binding bars

为研究带约束拉杆方形钢管混凝土短柱偏压的工作机理,采用考虑材料泊松比变化、钢管和核心混凝土界面作用及钢管残余应力的有限元模型,利用有限元软件ABAQUS对其偏压受力全过程进行分析.从横向变形、荷载-竖向位移曲线、核心混凝土纵向应力分布、钢管与核心混凝土的相互作用、约束拉杆的影响等方面讨论了带约束拉杆方形钢管混凝土短柱偏压工作机理.结果表明:有限元计算结果与试验结果吻合较好;设置约束拉杆可减小构件的横向挠曲变形,改变截面的变形模态,增强钢管对核心混凝土的约束效应,提高短柱的偏压承载力和延性;约束拉杆间距越小,短柱的延性越好,偏压承载力越大;泊松比对短柱偏压承载力具有一定影响,残余应力则对其几乎无影响.

To investigate the eccentric compressive mechanism of the square concrete-filled steel tubular（ CFT） columns with binding bars,the finite element softw are ABAQUS is adopted to analyze the eccentric compressive progress of the square CFT columns. The effects of the Poisson＇s ratio,the interaction betw een steel tube and core concrete,and the residual stress of the steel tube are considered in this finite element model. The mechanism of the square CFT columns with binding bars is discussed in consideration of the lateral deflection,the relationship of the load and the vertical displacement,the longitudinal stress distribution of core concrete,the interaction betw een steel tube and core concrete,and the effect of the spacing of binding bars. The results show that the calculation results of the finite element model are in agreement with the experimental results. The binding bars can confine the transverse deformation of steel tube,change the deformation mode of the cross section,improve the core concrete confinement from the steel tube,and increase the bearing capacity and the ductility of the columns. With the decrease of the spacing betw een binding bars,the peak load and the ductility increase. The Poisson＇s ratio has some influence on the peak load,while the residual stress of the steel tube has almost no any impact.