带脱空的钢管混凝土短柱受剪性能有限元分析

Influence of Gap on Mechanical Performance of CFST Members Subjected to Combined Axial Compression and Shear Force

基于合理的材料本构模型和边界条件,考虑外钢管与核心混凝土之间的组合作用,建立带脱空的钢管混凝土(CFST)短柱在压剪受力状态下的有限元分析模型(FEM).研究脱空率、剪跨比和轴压比对试件受剪性能的影响,提出考虑脱空率及轴压比影响的带脱空钢管混凝土受剪承载力简化计算模型.结果表明:脱空削弱了CFST柱在弹塑性工作阶段的受剪性能,且降低了其抗剪承载力;随着剪跨比增加,脱空对试件在纯剪及压剪作用下的抗剪承载力影响降低;当脱空率小于0.2%时,随着轴压比的增加,试件抗剪承载力线性增长.

A finite element model(FEM)of concrete filled steel tubular(CFST)member was established based on proper constitutive relation and boundary conditions.The composite actions between the outer steel tube and core concrete was taken into account,and a gap between the core concrete and steel tube was introduced into the FEM.Effect of the gap ratio,span to depth ratio,and axial compression ratio on the shear behavior of CFST members under combined axial compression and shear force was studied.A simplified model considered the effects of the gap ratio and axial compression ratio was proposed to predict the shear strength of CFST members with a gap.The numerical study indicates that the existence of the gap reduced the shear strength of the members on the elastic plastic stage,and decreases the ultimate shear strength of the members;with the increase of the span to depth ratio,the influence of the gap on the shear strength decreases.When the gap ratio is less than 0.2%,the shear strength increases with the increase of the axial compression ratio.